CAN any president govern? As Americans watch the Democratic primary scramble and await the fall electioneering, many thoughtful students of the US political scene are asking: Regardless of whether President Reagan or the Democratic nominee emerges victorious in November, does the present political system enable him to exercise the leadership needed to cope with today's critical problems?
Behind the query lies a widely held view that government is not working as it should. Political experts of both liberal and conservative persuasion - academic scholars, government officials, legislators, ex-presidents - are talking of the ''stalemate'' caused by the conflicts between Congress and the presidency. And they are exploring, studying, and debating a range of reforms, including changes in the US Constitution, as a possible way out of the dilemma.
''Our institutions are out of date,'' says former Democratic Rep. Richard Bolling. ''They are not organized in a way that enables them to deal well with our problems.''
''It's very hard today for a president to govern the country,'' comments John Gardner, author and founder of Common Cause. ''Part of the problem goes back to fragmentation - all the organized special interests that operate with no serious attention to the common good and paralyze the process of governing.''
''Government works when you have a president with a strong mandate who knows what he wants to do, and that happened in 1981,'' says political scientist James Sundquist of the Brookings Institution. ''But there has been deadlock since.''
''The American political system faces a pervasive crisis of self-confidence that only the rarest kind of leadership can overcome,'' writes historian James MacGregor Burns in his new book, ''The Power to Lead.'' ''The symptoms of the crisis take the long-observed form of political disarray, institutional stalemate, and governmental ineptitude and impotence.''
The Founding Fathers established a system of separation of powers to safeguard against tyranny. But many argue that today, the United States no longer lives in isolation and no longer dominates the world economically and militarily. It therefore cannot afford the luxury of government immobility.
The stalemate is seen in the inability of the legislative and executive branches to control the huge budget deficit and mounting national debt, in the failure in more than 10 years to achieve a nuclear arms control agreement, and in the difficulty of overhauling immigration law in the face of an unrelenting influx of illegal aliens.
Other problems defying government action include an antiquated tax system, deterioration of the nation's infrastructure, absence of handgun control, incalculable waste in arms procurement, and a financially burdensome social security system.
Not all political observers would say that this adds up to a crisis of leadership.
''Government is not in deadlock, but in a heterogeneous, pluralistic society in which that pluralism is well represented in the White House and Congress. Consensus building today is an arduous task,'' says Stephen Wayne, a presidential scholar at George Washington University. ''The president has to do more to achieve less - limiting his agenda and moving the most controversial items the most quickly.'' But, Professor Wayne suggests, the president is increasingly forced to practice ''crisis diplomacy,'' awaiting - even generating - a crisis before he is able to act. The inherent danger in this, he says, is that ''the president will exaggerate crises in order to mobilize support.''
Experts agree that governing has grown more difficult because today there are many more organized players in the political arena. Myriad special-interest groups have arisen to accommodate the demands of an increasingly pluralistic society. Institutions have weakened and power is more dispersed.
Political parties, in particular, have declined in importance in the past few decades. The parties once played a key role in controlling interest groups, mediating differences, forging consensus on policy, and, above all, nominating presidential candidates. They also used to provide cohesion within Congress.
But with the advent of direct primaries, party organizations at all levels have lost much of their power to select national convention delegates and deliver them to a candidate. As a result, presidential and congressional candidates develop their own organizations and, when they win, do not feel themselves beholden to the party. Jimmy Carter was a classic example.
Since the mid-1960s, moreover, party identification has weakened. The number of independent voters has grown. Many Americans today split their tickets. Even newspapers, which were once published by parties, now pride themselves on their independence and tend to endorse candidates across party lines.
The heightened independence of voters and candidates has been reinforced, in turn, by the emergence of television as the prime forum of American politics. TV has replaced the political party as the key means of reaching the largest number of voters. Presidents and other leaders now are selected or defeated on the strength of their performance on TV. Personality often becomes paramount over issues and policies.
Congress also has been weakened by fragmentation in the wake of reforms. The decline of party loyalty has diminished the power of congressional leaders. Committee chairmen have lost much of their control over the almost numberless subcommittees. The result has been loss of discipline and cohesion.
''The biggest problem - and this is a new development for the President - is knowing whom to deal with in Congress,'' says Rep. Richard B. Cheney (R) of Wyoming. ''Ike could deal with (House Speaker Sam) Rayburn and knew he could deliver. Today the President is not sure anymore.''
Contributing to the diffusion of power in Congress is the rising tide of special-interest groups since World War II capable of influencing public policy. Thousands of business, labor, trade, farm, maritime, professional, educational, and other groups are competing with each other and demanding government favors. They exert power in Congress by carefully dispensing campaign funds through the political action committees (PACs), which have proliferated since the post-Watergate campaign finance reforms. Lawmakers then often become hostage to the groups.
''What corrupts American democracy most these days is PACed interest groups, '' writes sociologist Amitai Etzioni in his book, ''Capital Corruption.'' ''While interest groups have haunted American democracy since its inception, only recently have they acquired the legal right to amass, openly, the resources needed to elect (or defeat) the nation's lawmakers.''
These special interests help create and perpetuate the so-called ''iron triangles'' - the close alliances formed between veteran members of Congress, the veteran middle-level bureaucrats in the executive branch, and the outside lobbies trying to influence those bureaucrats. Presidents and their Cabinet secretaries find these alliances, cultivated over years, are beyond their control.
''The Cabinet member can hardly do anything about it,'' says Mr. Gardner, a former secretary of Health, Education, and Welfare. ''These are people who have known each other for years. They have seen Cabinet secretaries come and go. They have seen presidents come and go. Republicans and Democrats come and go. It's permanent, invisible Washington functioning.
''That is the reason each president, I don't care what his party, sometime in the first week or two, concludes that the buttons on his desk aren't connected to anything.''
Perhaps the greatest obstacle to concerted government action is the fact that Congress, following the confrontation with President Nixon, has striven to reassert its authority and redress the imbalance of the ''imperial presidency.'' Thus, it has adopted a Congressional Budget and Impoundment Control Act to enable it to compete with the White House in drafting the federal budget; widely extended the legislative veto (now challenged by the Supreme Court); and passed a War Powers Resolution to curb the president's unilateral power to involve the country in war.
Although opinions differ over the merits of the War Powers Act, analysts seem to agree that legislators often exceed their authority above all in foreign affairs. In recent years the president, who under the Constitution is charged with executing foreign policy, has found himself blocked on such questions as military aid to Turkey, covert operations in Angola, and trade with the Soviet Union. President Reagan, too, is battling for his Central America and nuclear arms policies.
''Whether one likes it or not, if the country is to speak with one voice that voice must be the president's,'' writes Mr. Sundquist.
If government is often stalemated, what can be done? Historian Burns argues that both the Constitution and the party system must be reformed. He suggests a substantial change in the Constitution that would make possible a ''team ticket'' by which a voter would cast a single ballot for president, senator, and congressmen. He also supports the proposal of former Rep. Henry Reuss (D) of Wisconsin permitting the president to choose senators and congressmen as Cabinet members.
In his recent book, ''A Different Kind of Presidency,'' Theodore C. Sorensen, a former special counsel to President Kennedy, proposes a bipartisan coalition government. The coalition president would commit himself to serve only one term and would select a vice-president from the rival party. Half of the new Cabinet and the White House staff also would be divided between the parties.
Other suggestions include forming a joint executive-legislative council and allowing Cabinet members to participate in floor debate. Then there are those hardy perennials: a parliamentary system, a six-year term for president, a four-year term for representatives.
Reflecting the current intellectual ferment, a Committee on the Constitutional System is working on a package of proposed constitutional and nonconstitutional reforms. Co-chaired by Washington lawyer and former White House counsel Lloyd Cutler, former Treasury Secretary Douglas Dillon, and Sen. Nancy Landon Kassebaum (R) of Kansas, the 250-member committee includes former top government officials, members of Congress, academics, and others - Republicans as well as Democrats.
''Opposition to constitutional reform used to come from the right,'' says Sundquist. ''Now the shoe is on the other foot. The conservative Republicans find their programs are not getting anywhere, and maybe they too would like government to be more decisive.''
The committee hopes that its recommendations, to be presented by the fall of 1985, will stimulate discussion as the nation prepares to celebrate the bicentennial of the Constitution in 1987.
While political observers see value in probing all possible options, few think that radical change of the Constitution is possible. Fashioned by men of brilliant intellect and highest purpose, the Constitution has stood the country well over a long period. Americans regard it almost reverently. Getting popular support for structural change therefore would be extremely difficult.
Many experts even question the wisdom of tampering with the Constitution.
''Ours is a many-splendored, as well as many-splintered, system,'' says presidential scholar Thomas E. Cronin of Colorado College. ''Tensions are inevitable and designed that way. The Constitution disperses power and invites struggle.''
Despite the inefficiencies and conflicts, Dr. Cronin says, ''We do not need political structural change. It's not a matter of whether the president should be stronger. Both Congress and the president need to be stronger, to recognize that they are parts of the same government, and to work together and collectively.''
Short of drastic constitutional change, however, are proposals and approaches that reform-minded analysts say could improve the political system and are achievable:
* Revive the power of the political parties in nominating presidents. This could be done by reducing the number and influence of primaries, by giving more weight to the caucus system, which enlists the party activists, and by increasing the share of delegates at the conventions drawn from among party leaders. This, it is felt, would foster the selection of more experienced and tested presidents.
* Repealing the 22nd Amendment of the Constitution limiting a president to two terms. This would strengthen the executive's hand in a second term.
* Reforming congressional campaign financing, just as it has been reformed for presidential campaigns. The flow of money to nonparty PACs could be reduced by removing the limits on contributions to parties and removing spending limits by parties on behalf of candidates.
* Developing a corps of professional governmental managers. Currently, every new president brings in a new team of administrators and policymakers in the departments and agencies. A permanent and experienced manager corps - such as exists in other democratic countries - would make for more professionalism in carrying out policies.
Beyond the institutional dilemma, however, lies the root problem: the fragmentation of society. Social thinkers see a growing urgency for a return to a sense of the collective good after a period of excessive individualism and self-preoccupation. Public apathy, they feel, needs to be dispelled and attitudes changed.
''We have done a splendid job of creating a pluralistic world, a world of live and let live,'' says Gardner of Common Cause. ''But we have not done a good job of how you hold pluralism together and build a framework for cooperation and collaboration.''
The ''test for citizens,'' writes Professor Burns, is not whether they can rid themselves of their allegiances to various special-interest groups, ''but whether they can transcend them when events call for a more general, national, even international conception of the public interest.''