Washington — Whoever is elected President of the United States three weeks from now probably will face a Congress that is only modestly less Democratic than the present one.
That is the expectation now shared by campaign strategists of both parties and in both houses of Congress.
In the home stretch of a campaign punctuated by exaggerated predictions on both sides of sweeping gains and losses, Republicans now are believed likely to make only limited inroads into the Democrats' 25-year control of the legislative branch.
The GOP is expected to pick up a net of six or fewer seats in the Senate. The Party's Senate campaign committee anticipates adding between three and six seats, and its Democratic counterpart figures it will lose no more than three.
Any such result would fall short of the 10 seats needed for Republicans to achieve their once-bright hope of winning a Senate majority this year.
In the House of Representatives, the GOP seems likely to capture a net of 17 to 20 seats. House Republican campaign coordinators foresee a gain of 17 or more seats, while Democrats expect to lose 20 or fewer.
A shift of this magnitude would put only a small dent in Democrats' current 114-seat edge in the 435-member House.
In the dreamy, drawing-board days of this election year, before the hard campaigning began, Republicans had talked optimistically of seizing control of the Senate and narrowing their deficit in the House enough to perhaps forge a conservative majority there.
The more sober, end-of-campaign expectations raise the prospect of more measured electoral changes on Capitol Hill, insiders say, for a couple of reasons:
* Republican presidential nominee Ronald Reagan, like President Carter, appears to have exceedingly short political "coattails.) GOP campaign strategists echo their democratic brethren in saying they expect little spillover assistance from the top of the party ticket.
"We may, indeed, be helping Ronald Reagan," an official of the National Republican Congressional Committee (NRCC) goes so far as to suggest. A large proportion of GOP congressional candidates, he says, is shown by polls to be running ahead of the presidential nominee in various localities.
* What is emerging on the campaign trail is not the much-heralded "conservative tide," but a more selective threat to individual lawmakers -- many , but not all, of them liberals -- who may have lost touch with their constituents.
At one end are long-term Democratic incumbents whose back-home ties and campaign skills may have been neglected in the long absence of a strong GOP challenge.
These include such House heavyweights as Democratic Congressional Committee chairman James Corman of California, Ways and Means Committee chairman Al Ullman of Oregon, and perhaps even majority leader Jim Wright of Texas -- allof whom are among House leaders targeted by the GOP.
Democratic senators in similar electoral peril may include Warren Magnuson of washington, the 35-year dean of the Senate, George McGovern of South Dakota, and Frank Church of Idaho.
Senior Republicans, too, are far from immune, as shown by the stiff challenges facing Sens. Jacob K. Javits of New York and Barry Goldwater of Arizona.
At the order end chronologically are junior Democrats elected in the Watergate-backlash election of 1974 from traditionally Republican areas that may now be ready to revert to their old GOP allegiances.
They include such prime targets as Sen. John Culver of Iowa, Rep. Robert Edgar of Pennsylvania, Rep. David Evans of Indiana, and Rep. Andrew Maguire of New Jersey.
The issues that stir the voters in this year's congressional races tend to have a local slant, party strategists say, but the inflation-burdened national economy is never far from the tongues of voters and candidates.
"The economy and inflation are No. 1," one Republican official reports. "Nothing competes with it."