It opened in a burst of bipartisan cooperation that produced quick action on social security reform and emergency recession relief. But the 98th Congress, which closed down for the year Friday, bogged down in a swamp of the biggest federal deficit in history.
The President, who had dominated the previous Congress and won major legislative victories, stepped into the background as the 98th was sworn in last January, with the Republicans narrowly holding onto the Senate and the Democratic majority 26 seats stronger in the House.
Having put his economic program into effect in 1981, Mr. Reagan asked little of the new Congress except for new weapons for the military, such as the MX missile, and no new taxes. He won on both points. Congress often grew feisty over his foreign exploits - including aiding rebels in Nicaragua and sending peacekeeping troops to Lebanon - but it never overruled him.
On federal spending, the President brandished his veto threat ''like the sword of an avenging angel,'' as House majority leader Jim Wright (D) of Texas once said. But when the major appropriations bills arrived on his desk, pared down but still higher than the White House budget, he signed them.
''Nineteen eighty-one was the Reagan revolution, and 1983 was the Reagan drift,'' quipped Rep. James M. Shannon (D) of Massachusetts.
''He's gotten virtually every important item he's asked for,'' said Senate majority leader Howard H. Baker Jr. (R) of Tennessee on the last day of the session, but he admitted that Reagan had not sought as much as in his first two years.
House Speaker Thomas P. O'Neill Jr. turned out a steady stream of rhetorical and legislative challenges to the President on the domestic front throughout 1983. ''We have stemmed the tide of the unfairness of the Reagan administration, '' the Massachusetts Democrat told reporters last week. But on foreign affairs, O'Neill the patriot prevailed over O'Neill the partisan. He backed the President - first on the placement of marines in Lebanon and eventually on the invasion of the Caribbean island of Grenada.
The leaderships of the two houses shifted slightly during the year, although the principals remained the same. The Democrats found themselves more firmly in control of the House, even if the speaker had to contend with rebellions within his party against keeping marines in Lebanon and with impatient new members who wanted fast action to cut deficits. Basically the House became mainline Democratic again, after a short hey-day for an alliance of Republicans and conservative Democrats. ''Let's face it,'' said House Republican leader Robert H. Michel of Illinois, ''the loss of 26 seats sure as heck didn't help our case any.''
Republicans were reduced to parliamentary delays, haranguing, and horse-trading to try to win points.
Senate Democrats recovered from the shock of losing their majority in 1980 and began to rail in a more unified manner against the President, especially on his Lebanon policy and deficits.
The biggest leadership changes of all remained under the surface on the Senate side after Majority Leader Baker's surprise announcement that he will retire at the end of 1984. The generally unruly and filibuster-prone upper chamber often grew unmanageable. Once a legislative snarl prompted the even-tempered Baker to proclaim that he was frustrated ''every day in every way.''
On the last day of the session he called the year a success because it was adjourning earlier than in any nonelection year since 1965.
The year's events left important marks on the institution of Congress. On Nov. 7, a bomb exploded in a hallway and shattered the relaxed atmosphere of the Capitol, perhaps permanently. A sex-and-drug scandal in the House raised questions about whether lawmakers must live by higher standards than private citizens. And a historic ruling by the US Supreme Court overturned the ''legislative veto,'' a 50-year-old practice by which Congress had delegated power to the executive branch while reserving the right to veto specific actions.
As the members packed their bags to leave Washington, the most glaring item of unfinished business was the mounting federal deficit. And many on Capitol Hill had their eyes on the White House.
''I would hope the President realized that we're going need his help if we're going to do anything at all about the deficit,'' said House Ways and Means Committee chairman Dan Rostenkowski (D) of Illinois, last week, just after the House killed a modest $8 billion tax proposal. The plan was aimed at reducing the deficit, expected to reach a record $207 billion this year.
The White House shot down Kansas Republican Sen. Robert Dole's trial balloon on cutting the deficit.
Ironically, says political scientist Norman J. Ornstein of the American Enterprise Institute, ''What is probably the greatest accomplishment of the Congress - social security reform - may also turn out to be the Achilles heel'' in cutting the deficit. The reform will make it tougher for lawmakers to cut cost-of-living increases, he said, because the public believes social security problems have been resolved. Budget experts agree that the government must reduce federal benefit programs if it is to reduce the deficit because such ''entitlements'' make up such a big share of federal spending.
If Congress failed to reduce the nation's red ink, it dealt with a variety of other issues.
* It passed 10 of the 13 appropriations bills needed to run the government, a big improvement over last year when it passed only six, and had to roll all other government spending into a continuing resolution.
* It agreed to almost all of the weapons the Reagan administration sought, except nerve gas. Even if total military funding was lower than the President wanted, Congress enacted the highest military appropriations bill in history, totaling $249 billion. Although the House passed a nuclear weapons freeze resolution, it approved money to build the 10-warhead MX missile. By the end of the session the only thing that seemed frozen was the nuclear freeze movement within Congress itself.
* An outpouring of congressional sentiment ushered out of office the confrontational Interior Secretary James G. Watt. The Senate confirmed William P. Clark as his replacement.
* On the final day Congress agreed to an additional $8.4 billion for the International Monetary Fund.
* Civil rights groups protested as Reagan fired three members of the US Civil Rights Commission, an advisory watchdog panel that had criticized his administration. But Congress and the White House compromised on a new, eight-person commission with four presidential and four congressional appointees.
A federal holiday for civil rights leader Martin Luther King Jr. was proclaimed, beginning in 1986.
* Women's economic rights became a hot topic, but most of the reform legislation remained unfinished. The House rejected the reintroduced Equal Rights Amendment.
When Congress returns on Jan. 23, it will face several other issues: natural gas deregulation; rewriting the Clean Air Act; and a bill aimed at protecting consumers from skyrocketing telephone bills following the breakup of American Telephone and Telegraph Company.