With just over 100 days to go before the fall elections, further Republican gains in the US Senate in 1982 look harder to come by.
GOP professionals still claim they will gain three or four seats, widening their present 54-to-46 seat margin over the Democrats. The Democrats, with 20 seats at risk compared with the Republican's 13, look for a net change of a seat or two, either way.
But a closer look, based on party strategists' and outside observers' appraisals, shows the Democrats strengthening their positions, and many of the GOP's earlier windows of opportunity closing on them.
The tardy, tepid economic recovery has given the Republicans little to boast about, with the benefits of Reaganomics still more promised than delivered. Yet the President's personal popularity still makes it difficult for the Democrats to attack him.
As a result the 1982 Senate races are, for the most part, hinging on local issues. National issues and party labels are often secondary. The contests are often on the nuts-and-bolts level of political warfare, where an incumbent's record, the challenger's age or maturity, fund-raising prowess, or ability to keep in touch with constituents are playing the dominant role.
Liberals, moderates, or conservatives appear to have no particular edge or handicap in races for US Senate.
Regional trends are hard to find. Two of the Republicans' three weakest seats - New Mexico and Utah - are in the West, supposedly a GOP stronghold. The other seat which the Democrats rate themselves as having a near-even chance to win is in the East. California, now leaning to the Republicans with San Diego Mayor Pete Wilson facing Democratic Gov. Edmund G. Brown Jr., could also turn the Democrats' way, some Democrats assert.
The Republicans see their best prospects for upsetting Democratic incumbents in Nebraska, Nevada, and Virginia. Some Republicans rate themselves even to win Democratic seats in Maine, Maryland, North Dakota, Ohio, Nevada, Florida, Mississippi, and Texas. Other GOP professionals, however, concede the Democrats the edge in these same seats.
Turnout could prove the key in the 1982 Senate races. Maine's Democratic Sen. George J. Mitchell is counting on interest in a nuclear referendum this fall to help turn out his kind of voter, to repel the strong challenge of Republican US Rep. David Emery. In states like Texas and New York, colorful governors' races could have a big impact on who goes to the polls.
Part of the GOP decline in prospects is due to the party's failure to produce strong rivals to face Democratic incumbents like Donald Riegle of Michigan, Daniel Moynihan of New York, and Spark Matsunaga of Hawaii. In other cases, the Democratic incumbents have just gotten down to reelection work - Robert Byrd in West Virginia, Quentin Burdick in North Dakota, James Sasser in Tennessee.
Some of the more moderate Republicans - John Heinz of Pennsylvania, William Roth of Delaware, Robert Stafford of Vermont, David Durenberger in Minnesota, Millicent Fenwick of New Jersey - are in the best shape. GOP seats now held by conservatives in California, New Mexico, Utah, are among the most in doubt.
In the South, all six seats at stake this fall are held by Democrats. Some Republicans contend that Florida's Lawton Chiles, now ahead, can be caught in the homestretch because of his self-imposed restrictions on fund-raising. They say that Texas incumbent Lloyd Bentsen now runs some 14 points ahead of GOP Congressman Jim Collins for the Senate seat, but that ''Collins runs more like a Texan, looks more like a Texan, and sounds more like a Texan'' than does Bentsen , and can catch the Democrat by November. Mississippi's venerable incumbent John Stennis is defeatable because of his age, Republicans say. But GOP victory will require a high percentage of the black vote for challenger Haley Barbour - a tough feat, since Barbour is closely linked to President Reagan, GOP strategists admit.
Both sides see the Virginia race for retiring independent Harry F. Byrd's seat as a near tossup, with each side claiming the edge. The Democrat, Lt. Gov. Richard Davis, is viewed as the more experienced, and has been a strong vote-getter in the past. Republican Rep. Paul Trible seems the beneficiary of Virginia's new conservative wave.
In the Midwest, the economy weighs heavily at all levels of the state contests. Republicans appear on the verge of losing a half-dozen governorships. GOP Senate incumbents Richard Lugar of Indiana, David Durenberger of Minnesota, and John Danforth of Missouri appear strong enough to weather the region's recession. But Ohio's Howard Metzenbaum and Michigan's Riegle clearly benefit from the economic hard times, and North Dakota's Burdick gains from the Midwestern farmers' plight.
The Republicans rate Burdick's seat a tossup. But a neutral North Dakota political observer says: ''Burdick's a likely winner - probably a big winner. NCPAC plans to spend $200,000 against him. But the farm economy will help Democrats in North Dakota, which has a tradition of swinging against the party in power in off-year elections.''
1982 Senate race Democratic incumbent seats
Dem GOP rating rating East Maine Mitchell 1 0 Md. Sarbanes 1 0 Mass. Kennedy 2 2 N.Y. Moynihan 2 1 Midwest Mich. Riegle 1 1 Neb. Zorinsky 1 -1 N.D. Burdick 1 0 Ohio Metzenbaum 2 0 Wisc. Pro xmire 2 2 West Ariz. DeConcini 1 2 Hawaii Matsunaga 2 2 Mont. Melcher 1 -1 Nev. Cannon 0 0 Wash. Jackson 2 2 South Florida Chiles 1 0 Miss. Stennis 0 0 Tenn. Sasser 1 1 Texas Bentsen 1 0 Va. H. Byrd 0 -1 W.Va. R. Byrd 1 0 Republican incumbent seats
Dem. GOP East Conn. Weicker 0 1 Del. Roth 1 2 N.J. Brady 1 1 Pa. Heinz 2 2 R.I. Chafee 1 1 Vt. Stafford 1 2 Midwest Ind. Lugar 1 2 Minn. Durenberger 1 1 Mo. Danforth 2 1 West Calif. Hayakawa 1 2 N.M. Schmitt 0 0 Utah Hatch 0 1 Wyo. Wallop 1 2 Rating system: 2 -- strong for incumbent party, 1 -- leaning toward incumbent party, 0 -- even, -1 -- in doubt, -2 -- likely loss.