President Reagan and congressional Democrats are hunkering down for the 1984 campaign season in a state of uneasy accommodation, pulling their punches and flinching from the risks of confrontation as they join in tiptoeing around some of the country's biggest problems.

It could all come unglued when Congress returns from its five-week summer recess on Sept. 12, especially if trouble flares abroad or if rising interest rates shatter the current congressional euphoria over the economy.

But, when the weary House and Senate bolted out of town Thursday night, Reagan and the Democrats appeared to have reached a point of contentious coexistence, with both sides angling for political advantage without pushing for a knockout blow.

"Chins out, elbows in," said a congressional aide.

In this climate, Reagan's program, while frayed at the edges, appears secure enough to last through next year's elections.

With the economy improving and with the shadow of the 1984 elections already hanging over Congress as well as the White House, "we're basically on hold from now on," as House Republican Policy Committee Chairman Dick Cheney (R-Wyo.) put it last week.

With an assist from some moderate Republicans, the Democrats succeeded during the first seven months of Reagan's third year in slowing the momentum of his drive to reshape the government by restraining domestic spending, building up the military and cutting taxes.

But they did not reverse the overall thrust of his basic program. Nor have they succeeded, without his at least grudging assent, in enacting any major initiatives of their own.

Reagan's tax cuts are still in place, with the Republican-controlled Senate having thwarted the Democratic House from capping the cut that took effect last month.

In defense, only the rate of budget growth has been slowed, with little harm to the arsenal of new weapons systems that Reagan wanted, including the controversial MX missile that Congress has at least tentatively approved.

And, while Reagan has been blocked from new cuts in social welfare programs and may have to swallow a couple of relatively modest new ventures, such as health insurance for the unemployed, restraint is still the rule.

Moreover, with the economy on the rebound and the administration pushing for a show of military force in Central America, Congress has also shifted its focus abroad, with varying degrees of concern in both parties over military intervention and arms control.

But, with the important exceptions of House votes for a nuclear freeze and for an end to the "secret war" over Nicaragua, the Democrats--outnumbered in the Senate and lacking enough votes in the House to override a veto--have largely avoided serious challenges to the White House.

Instead they have tried to get all they can by compromising on "must" legislation while seeking to build a record for next year's elections on the rest of their legislative agenda.

In a curious way, even House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) acknowledged Reagan's continued domination of the political landscape as he reviewed Congress' record so far this year. In summing up what the House has accomplished, he said it had "prodded the administration toward policies of fairness at home and peace abroad."

What has been achieved has come largely from bipartisan compromise on issues ranging from Social Security financing and jobs legislation to the MX missile and military aid to El Salvador.

Issues that are not amenable to such give-and-take, such as Reagan's cost-cutting proposals for social welfare programs and the Democrats' plans for major job-creating initiatives, have proved to be foredoomed.

And some of the biggest and most intransigent problems of all, such as how to cope with annual federal deficits nudging $200 billion over the next few years, have been brushed aside by both the White House and Congress. To Rep. Leon E. Panetta (D-Calif.), it's beginning to look like a chess game.

"We've checked some of the president's moves, but we haven't reversed direction or changed policy . . . . Frankly, the president and Congress are engaged in a fudging process in postponing tough decisions to a later time, . . . probably after the 1984 elections, when it may be too late," Panetta said.

Senate Finance Committee Chairman Robert J. Dole (R-Kan.) was no more charitable in his assessment of both the president's and Congress' failure to come to grips with the deficit problem.

"Increasingly it seems we are drifting into sort of an aimless stupor when it comes to economic policy," said Dole, although he and his own committee have been dawdling over relatively modest deficit-reducing tax increases that were mandated by the recently passed congressional budget.

Similary, Sen. Patrick J. Leahy (D-Vt.) complained that congressional claims of restraint on free-wheeling Pentagon spending practices are hollow.

"The Pentagon will call a press conference to say they've cracked down on $200 stepladders, or whatever, and then a House committee will show they've cooked the books to the extent of $500 million on the F18. So everyone says, hurray, we'll have no more $200 stepladders. We're not going after the major problems; they just roll on," Leahy griped.

If there's been bobbing and weaving to avoid confrontation, it's at both ends of Pennsylvania Avenue.

The Democrats have acquiesced in trimming domestic spending bills in order to get Reagan's signature, supplied enough votes to give the president most of the new military weapons systems he wants and joined Reagan in just about every "bipartisan" initiative that he has attempted to launch.

But, at the same time, Reagan, despite oft-repeated veto threats, has signed or indicated he will sign all five of the appropriations bills Congress has sent him this year, even though several don't conform to his spending priorities.

Moreover, after winning bipartisan agreement on a Social Security rescue plan that included tax increases he hadn't wanted, he cooperated with Democrats in drafting an anti-recession jobs program that had never been even a footnote on his congressional wish-list.

Most recently, the administration, working on several fronts to blunt a perception of unfairness to the poor, assented just before Congress left town to an extension of the government's soon-to-expire surplus food distribution program and emergency action to keep jobless benefits flowing to thousands of the long-term unemployed.

In the case of the congressional budget, passed by both the Republican Senate and Democratic House over Reagan's protests, the White House has simply ignored it and used Reagan's budget for veto-guideline purposes. Although Congress unceremoniously junked Reagan's budget early in the year, the Democrats have been forced to keep an eye on it for bills they want signed.

A major reason for the caution, perhaps the dominant one, is the 1984 elections and what one congressional aide referred to, in the Pentagon vernacular, as "MAD," for mutually assured destruction.

For instance, in social welfare spending the Democrats can assert their concern for the poor, and Reagan's lack of it, by sending him big, fat spending bills that he is bound to veto. But Reagan can turn around and use the measures as evidence that the "big-spending" Congress doesn't care about the average taxpayer. In that kind of political equation, everyone comes out bloodied.

Political uncertainty is exacerbated by economic uncertainty. Congress may be becalmed now by the economy's snappy rebound, but both parties are jittery over rising interest rates and the impact they could have on the recovery if they continue. A similar midsummer jolt from interest rates marked the beginning of the end of Reagan's honeymoon with Congress in 1981.

The spirit of accommodation will be severely tried when Congress tackles its most controversial spending bills, including defense and the huge bill for employment, health, education and welfare, where Democratic leaders reportedly want to draw the line on bowing to Reagan.

In all probability, many of these big-ticket spending bills will have to be wrapped into an omnibus "continuing resolution" that must be passed to keep the government operating after the start of the new fiscal year Oct. 1.

The uneasy state of relations was underscored when the lawmakers, before going home, empowered their leaders to call Congress back into session in case of emergency--a power normally left to the president. It was the first time since Reagan came to town that the Democrats demanded equal access to the call button.