Republican presidential nominee Ronald Reagan and GOP congressional leaders staged what amounted to a family portrait day on the Capitol steps yesterday -- a picture of well-disciplined harmony to contrast with what Reagan called the "legislative chaos" of the Democrats.

Flanked by scores of congressional candidates and running mate George Bush, Reagan unveiled a five-point "solemn covenant" of joint GOP action that would include a tax cut, spending reductions, more jobs and a stronger national defense.

It was the standard fare at he 1980 Republican campaign, wrapped up in fancy paper, just gauzy enough to keep the cameras from catching any scowls or focusing on any sharp edges.

In any case, the main point of the event was not specific legislative proposals, but rather the novelty of such anendeavor between presidential and congreassional tickets, a feat that the more divided Democrats are unlikely to attempt to duplicate.

"They're all running away from their nominee," crowed Senate Minority Whip Ted Stevens (Alaska) as he talked with reporters afterward. "Another cotton-candy media event," huffed Senate Majority Leader Robert C. Byrd (W.Va.)

If it was a media event, the Republican made the most of it, even though the crowd was mostly congressional aides who did not exactly bubble over with spontaneous enthusiasm. Applause was frequent but thin.

Standing on the stately West Front steps from which he hopes to be inargurated on Jan. 20, Reagan looked down Pennsylvania Avenue, pledging that the Republicans would turn it into a "two-way street again."

Under the Democrats, said Reagan, the avenue has become a "moat dividing the unresponsive congressional leadership from a president who is often isolated and unable to fulfill the primary responisbilities of his office."

"Never before in history have so many proposals from the White House been ignored or defeated in the Congress," the Republican nominee added, contradicting Democratic claims of substantial joint achievements over the past four years. "Never before has a president been more remote from the members of his own party," he continued.

As for the Republicans' joint pledge, which is to be taken by congressional candidates as well as Reagan and Bush, it reads in full:

"Substantial cuts in the amounts of money the Congress spends on itself, so that Congress can set an example in belt-tightening for the rest of the government.

"Selective cuts in government spending to reduce waste, fraud and abuse to a minimum, and to fight inflation while protecting those in need.

"An across-the-board individual income tax cut and increased incentives for savings, investment and capital recovery, which will put this country back on the road to prosperity.

"All-out efforts to encourage more private investment and more permanent jobs, especially in our central cities.

"Stepped-up defense efforts to make our foreign policy credible and to secure peace and stability in the world."

Republicans estimated that more than 250 lawmakers and would-be lawmakers attended, most of them lingering afterward to have individual campaign pictures taken with Reagan and Bush.

For House members there was also a get-together with representatives of political action committees that dole out money during campaigns -- a kind of one-stop shopping center for the PACs in their efforts to win influence in Congress with campaign contributions. Unlike the ceremony on the Capitol steps, this was not, campaign officials said, a media event.