ILLINOIS

DESPITE HIS STATE having the second-highest unemployment in the country and his opponent -- former Sen. Adlai E. Stevenson III (D), 51 -- having a great Illinois name, Gov. James R. Thompson (R), 46, is rolling toward becoming the first three- time winner of that office. Today's Chicago Tribune poll gives Thompson a 53-34 percent lead.

In the nationally spotlighted House race, Minority Leader Robert H. Michel (R) went into the final days about 10 points ahead of union lawyer G. Douglas Stephens (D), who sought to turn Peoria's 15 percent jobless rate into a rejection slip for Michel, but was outspent at least 4-1.

Four other Republican incumbents face sharp challenges. Rep. Paul Findley (R) is up against lawyer Richard J. Durbin (D) in a heavy-spending race where the debate goes beyond economic problems to Findley's publicized support of Palestinian causes. Rep. Daniel B. Crane (R) meets John Gwinn (D), a lawyer from Champaign, near the University of Illinois, which is newly added to the district. Freshman Rep. Lynn M. Martin (R) faces a test in the Rockford area (18.5 percent unemployment) from Carl R. Schwerdtfeger (D), a farmer and teacher, and veteran Rep. George M. O'Brien (R) is opposed by lawyer Michael A. Murer (D) in Joliet.

But the Democrats' best chance for a gain is in the open seat, where state Sen. Kenneth G. McMillan (R), a staunch conservative who defeated moderate Rep. Tom Railsback (R) in the primary, is struggling to hold off labor- backed Rock Island lawyer Lane Evans (D).

INDIANA

WITH A 5-1 SPENDING advantage and a tough, aggressive campaign, Sen. Richard G. Lugar (R), 50, appears set to win a second term over Rep. Floyd Fithian (D), 53, who has tried to make the race an economic referendum for discontented farmers and jobless workers. Both men are scholars -- Lugar went to Oxford and Fithian taught at Purdue -- but their TV ads have been slash-and- burn, with Lugar seemingly the survivor.

Rep. Philip R. Sharp (D), a "Watergate baby" of 1974 who has held on longer than anyone expected, may survive again, despite a Republican gerrymander that was supposed to set up a victory for former Shelbyville Mayor Ralph Van Natta (R). Rep. Joel Deckard (R) was embarrassed when he ran his car off the road three weeks ago, but post-accident polls reportedly show him still in front of Bloomington Mayor Francis X. McCloskey. (D)

IOWA

AFTER 14 YEARS of Gov. Robert Ray (R), Democrats thought they had a chance for victory, with former U.S. Attorney Roxanne Conlin, 38, leading Lt. Gov. Terry Branstad (R), 35, in the polls. Then Conlin revealed that she and her real-estate-developer husband had used tax credits to avoid paying any state income tax in 1981, and she plummeted. But as that issue faded, the debate shifted to her proposal for state-financed public works projects and Branstad's support of antiabortion activities -- one of many differences he has with Ray's school of moderate Republicans. The final Iowa Poll of the Des Moines Register and Tribune, published today, shows Branstad leading by a shaky 45- 43 percent.

The standout House race is the rematch between freshman Rep. Cooper Evans (R) and Black Hawk County Supervisor Lynn G. Cutler (D), national vice chairman of the Democratic Party. Evans barely won in 1980, and the district was made tougher for him by the addition of the University of Iowa and by farm-equipment layoffs continuing this week in Waterloo. But late reports put Evans a shade in front.

KANSAS

REGARDED AS ONE of the most vulnerable Democratic incumbents, because of charges he broke a campaign promise to support a death-penalty bill, Gov. John Carlin, 42, has battled back in his race with real estate developer Sam Hardage (R), 43. His advocacy of an oil and gas severance tax has won him support even in Republican areas, and he may eke out a second-term victory.

State Rep. Jim Slattery (D) has apparently gained the edge on former state GOP chairman Morris Kay (R) for the seat of retiring Rep. Jim Jeffries (R).

MICHIGAN

CONSERVATIVE BUSINESSMAN Richard H. Headlee (R), 52, campaigning hard against the moderate-liberal social and economic views of both retiring Gov. William G. Milliken (R) and Democratic nominee Rep. James J. Blanchard, 40, has moved into contention by gambling that frustrated and recession-plagued Michigan voters are ready for a decisive turn to the right. As in the primary, when h upset Milliken's candidate, Headlee is being helped by former Gov. George Romney. But Democrats are confident that Blanchard, best-known as the sponsor of the Chrysler bailout bill, will end 20 years of Republican control in Lansing and perhaps trigger a statewide sweep. The final Detroit News poll, published today, shows Blanchard leading, 46-39 percent among likely voters.

The same poll shows Sen. Donald W. Riegle Jr. (D), 44, rolling to a second term over ex-Rep. Philip E. Ruppe (R), 56, by a margin of 54-35 percent.

Riegle's strength could help the Democrats in two hard-fought House races. Their best chance may lie in the rematch between freshman Rep. Jim Dunn (R) and ex-Rep. Bob Carr (D) in a district redrawn to include hard-hit and Democratic Pontiac. It would take more of a tide for Rep. Harold S. Sawyer (R) to lose to state Sen. Stephen V. Monsma (D) in Grand Rapids.

Sander Levin (D), who lost twice for governor, will get Blanchard's House seat as a consolation prize.

MINNESOTA

WHEN RUDY PERPICH (D), 54, the Iron Range dentist, was ousted from the governorship in 1978 by Gov. Albert H. Quie (R), his political career seemed finished. But now Quie is going into voluntary retirement after four years of brutal budget battles, and Perpich is poised for a comeback over investment banker Wheelock Whitney (R), 56.

Sen. David Durenberger (R), 48, ahead early in his bid for a second term, slumped under the liberal rhetoric and record $5.7 million spending of department store heir and Rockefeller in-law Mark Dayton (D), 35, but has resurfaced as a slight favorite. Republicans say Durenberger is about nine points up -- enough to withstand everything but a heavy Democratic tide.

Three Republican House seats are under siege: Rep. Tom Hagedorn (R) vs. state Sen. Timothy J. Penny (D); Rep. Arlan Stangeland (R) in his third consecutive race with former state Rep. Gene Wenstrom (D); and Rep. Arlen Erdahl (R) in a rematch with state Sen. Gerry Sikorski (D). Democrats hope for at least one pickup.

MISSOURI

ALTHOUGH OUTFINANCED at least 3-1, state Sen. Harriett Woods (D), 55, has come from far back, with an aggressive campaign, to pull even with -- or slightly ahead of -- Sen. John C. Danforth (R), 46, in the final week of the campaign. Republicans hope Danforth's decision to swing back at his challenger will give him a second term, but it looks chancy.

Reps. Ike Skelton (D) and Wendell Bailey (R), were thrown together by redistricting, and the edge, though narrow, is to Skelton. Freshman Rep. Bill Emerson (R) seems to be withstanding the challenge of state Rep. Jerry Ford (D) in normally Democratic territory. State Rep. Alan Wheat (D), a black, is favored over state Rep. John A. Sharp (R) as successor to retiring Rep. Richard Bolling (D).

NEBRASKA

YESTERDAY'S OMAHA World-Herald poll, taken after last week's Reagan visit, confirmed the worst fears of Republicans. It showed Vietnam War Medal of Honor winner Bob Kerrey (D), 39, a restaurant operator, leading Gov. Charles Thone (R), 58, 47-37 percent. A sagging farm economy which has forced an emergency post-election legislative session, combined with Kerrey's charismatic personality, could make Thone an underdog in his fight for a second term, but a smaller poll taken for the Lincoln Journal gave Thone a five-point lead. Call it a tossup.

Sen. Edward Zorinsky (D), 53, who votes often with the president, is having an easy time with retired Air Force general Jim Keck (R), 61. Democratic vote-turnout efforts may help former state Sen. Richard M. Fellman (D) in his rematch with freshman Rep. Hal Daub (R), but Daub is favored.

NORTH DAKOTA

SEN. QUENTIN N. BURDICK (D), seeking a fourth term at age 74, has offered to fight anyone who thinks he is too old for the job, has singed NCPAC for its negative ads, and has tagged his opponent, Gene Knorr (R), 42, as a Washington business lobbyist recently returned to the state. The aggressive defense seems to be working. Newspaper polls show Burdick winning, 61-22 percent.

OHIO

TOUGH (12.5 PERCENT) unemploy ment and weak Republican candidates are making some in the GOP fearful that 1982 could be "another 1958," a wipeout year for their party. Democrats, said Cuyahoga County GOP chairman Robert Hughes, "are trying to punish all Republicans for Reagan."

That is true of the governor's race, where former Peace Corps director and lieutenant governor Richard F. Celeste (D), 44, is strongly favored to defeat Rep. Clarence J. Brown (R), 55, and succeed retiring Gov. James A. Rhodes (R). It is also true of Sen. Howard M. Metzenbaum's (D), 65, sweep toward a second term over state Sen. Paul E. Pfeifer (R), 39.

But the sweep may not cost the GOP House seats. Only one incumbent seems threatened, freshman Rep. Ed Weber (R) of Toledo. But former Carter White House aide Marcy Kaptur (D) is struggling to overcome a big financial edge and a late start. Similar factors make state Sen. Michael Dewine (R) a favorite to defeat County Commissioner Roger D. Tackett (D) in Brown's old district. And Republicans have a fair-to-good chance of beating freshman Rep. Bob Shamansky (D) in Columbus with state Sen. John R. Kasich (R).

SOUTH DAKOTA

GOV. WILLIAM J. JANKLOW (R), 43, an activist on water and economic development projects, is expected to roll over state Sen. Mike O'Connor (D), 53, and gain a second term.

South Dakota loses one of its two House seats to reapportionment, and Rep. Thomas A. Daschle (D) was leading Rep. Clint Roberts (R) by at least a small margin even before a pinched nerve forced Roberts off the campaign trail and into the hospital for more than a week.

WISCONSIN

IN A STRAIGHT-OUT liberal-conservative test between a Democrat who warns that taxes may rise and a Republican who says "never," former assemblyman and secretary of natural resources Anthony S. (Tony) Earl (D), 46, is beating businessman Terry J. Kohler (R), 48, son and grandson of former governors, in the race to succeed retiring Gov. Lee Sherman Dreyfus (R). Earl has almost all the newspaper endorsements and a lead that polls say may top 15 points.

Sen. William Proxmire (D), 67, would consider that a squeaker, but he can count on his usual healthy margin for a fifth full term over state Sen. Scott McCallum (R), 32.

Three serious House races involve Reps. Robert W. Kastenmeier (D), Steve Gunderson (R) and Toby Roth (R), but all three are favored.