Washington — Robert C. McFarlane is emerging as a powerful, if unflamboyant, national-security adviser to the President, with a weighty voice in foreign-policy making. With Congress away and President Reagan vacationing in California, it has not gone unnoticed that ``Bud'' McFarlane is out front these days, dominating many August headlines:
Recently he met with South African Foreign Minister Roelof Botha in Vienna to signal that Mr. Reagan would be unable to withstand the congressional moves for sanctions unless South Africa put through reforms to change its system of apartheid.
Following South African President Pieter W. Botha's subsequent hard-line speech, Mr. McFarlane delivered the White House's cautious response in Santa Barbara, Calif., the next day and later appeared on Cable News Network to voice disappointment over the failure to lift the state of emergency in South Africa.
This week he gave a speech to local civic groups in Santa Barbara rebuking Soviet actions on security issues and warning that it would be hard to improve Soviet-American relations unless Moscow changed its approach.
Such visibility is in sharp contrast to McFarlane's low-key style when he first took over the post in October 1983. An ex-Marine lieutenant colonel, McFarlane is a quiet-spoken but tough-minded man who had won a reputation as a loyal, indefatigable presidential aide content to work unobtrusively behind the scenes to resolve conflicts within the bureaucracy.
But, especially since Reagan's second term began, McFarlane has gradually assumed more influence -- drafting position papers, chairing working groups, and taking charge in such situations as the Beirut hostage crisis. Today he frequently briefs the press, with television cameras rolling, and appears on TV talk shows.
Two things are seen to account for McFarlane's growing role.
One is the competition with White House chief of staff Donald T. Regan and the desire to make himself indispensable and keep his independence. It is the normal bureaucratic reaction of anyone in a White House environment not to be swallowed up by the chief of staff. Informed sources say McFarlane is consciously battling to prevent this from happening.
But beyond such personal considerations, diplomatic experts see McFarlane's rise of influence as a natural process.
In the beginning, they say, presidents are often under pressure from the secretary of state to ensure that the national-security adviser remains an ``inside guy'' and not a visible foreign-policy spokesman who can undercut the secretary.
For example, Alexander M. Haig Jr., Reagan's first secretary of state, made certain he would not be upstaged by then-national-security adviser Richard Allen.
But then an irresistible dynamic sets in. For one thing, the president begins to think of the secretary of state as loyal to the department he heads, while the national-security adviser is his own man.
For another, the security adviser is the one who sees the president every day and is more privy to his instincts and interests and to the political constraints on him, including pressures that come from departments other than defense and state.
``So the president comes to regard his national-security adviser as a safer spokesman than the secretary of state and so eventually the national-security adviser begins to emerge,'' says Peter Szanton, an expert regarding National Security Council.
``It's not at all surprising,'' says Philip Odeen, a former aide to then-Secretary of State Henry Kissinger. ``The adviser has to play a significant role, because no one agency is looking after the President's best interests. The National Security Council can take account of military, political, and economic factors, which are especially important in today's more complex environment.''
Diplomatic observers do not see McFarlane's increased role as causing problems in relations with Secretary of State George P. Shultz or challenging the Cabinet system of government on which Reagan relies. In previous administrations rivalries and frictions, developed between the holders of the two jobs -- between Mr. Kissinger and Secretary of State William P. Rogers, for example, and between Zbigniew Brzezinski and Secretary of State Cyrus Vance.
But administration officials say McFarlane and Mr. Shultz, who see eye to eye on many issues, have developed a good sense of teamwork.
In fact it is Defense Secretary Caspar W. Weinberger who seems to have become a secondary figure, now that the military buildup is leveling off and he can no longer push increases in defense spending.
Still, putting oneself out front has its hazards. McFarlane's foray to Vienna ended in diplomatic embarrassment when the South African government failed to respond to American importunings.
The incident recalls Vice-President Walter F. Mondale's trip to Vienna in March 1977 to deliver a similar anti-apartheid message to the South Africans. The Carter administration was similarly rebuffed.