ILLINOIS

NEITHER Gov. James R. Thompson (R) nor Sen. Charles H. Percy (R) is likely to come close to matching the record more-than-a-million-vote margins they won in their last campaigns. But neither is likely to lose.

Thompson, 41, a GOP presidential possibility, has been kept somewhat on the defenseive on the tax issue by challenger Michael J. Bakalis (D), 40, the state comptroller, and the combination of a light vote and some problems with the regular GOP organization would give Thompson a scare. His defeat would be a major upset, however.

Similarly with Percy, 58, who is opposed by Alex R. Seith (D), 43, a moderate Democrat making his first campaign. Percy, too, has shown signs of vulnerbility, but Seith is fighting a huge recognition problem with limited funds.

Perennially endangered Rep. Abner J. Mikva (D) may have a slight edge in this year's battle for survival, and Democrats are throwing their first serious challenge in years at veteran Rep. Robert McClory (R). Republican Daniel B. Crane is a narrow favorite to defeat Democrat Terry L. Bruce for the seat of retiring Rep. George E. Shipley (D) in the district that is the subject of The Post's continuing political serial. INDIANA

WITH NO major statewide races, attention centers on battles in Democratic-held districts. Freshman Rep. David L. Cornwell (D) is no better than an even bet against the challenge of former state Rep. H. Joel Deckard (R). Rep. David W. Evans (D) may have a harder time than he did two years ago against David G. Crane (R), brother of Rep. Philip M. Crane (R-Ill.), the GOP presidential contender, and Illinois congressional candidate Daniel B. Crane. Republicans talk of upsetting House Majority Whip John Brademas (D) and Democrats have a strong woman candidate against Rep. John T. Myers (R), but in both cases the odds are against their success. IOWA

ASIS customary, Gov. Robert D. Ray (R), 49, whose popularity has contined to grow during his 10 years in office, is far ahead in his reelection race. A September Des Moines Register poll gave him a 69-24 percent lead over Jerome Fitzgerald, 36, majority leader of the Iowa house.

Sen. Dick Clark (D), 48, is favored for a second term over former Lt. Gov. Roger Jepsen (R), 49, a conservative with strained relations with the moderate Ray. Jepsen weathered a period of questioning on personal and campaign finances during the summer and has regained the offensive, critizing Clark on everything from fiscal and farm policy to African issues. But Clark held a 12-point lead in the September poll and is viewed as the likely winner, albeit by a small margin.

Rep. Michael T. Blouin (D) is the most threatened House incumbent, with the GOP scoffing at Democratic claims that Rep. Jim Leach (R) could be an upset victim. KANSAS

WITH GOV. Robert F. Bennett (R), 51, leading his opponent, state house Speaker John Carlin (D), 38, in his bid for a second term, most of the excitement in Kansas politics centers on the races of the two women.

Nancy Landon Kassebaum, daughter of revered one-time presidential candidate Alf M. Landon, came out of a large Republican field with the nomination to succeed retiring Sen. James B. Pearson (R). Riding that win and a personable campaign style, she moved ahead of ex-Rep. Bill Roy (D), a narrow loser in a 1974 Senate bid. Three late-summer polls put her head at 6 to 15 points. But Roy has fought back, and last week his campaign charged that Kassebaum had paid little income tax the last three years, despite listing her net worth at over $2 million. She charged the Democrat was "playing dirty," but the effect of the issue on what both sides see as a close race cannot yet be measured.

The second spotlighted woman is Rep. Martha E. Keys (D), who has won two tough races in a traditionally Republican district. Keys is trailing challenger Jim Jeffries (R) in published polls, but Democrats think her personal campaigning may be able to pull it out again. Democrats also hope to win the close race in the district of retiring Rep. Joe Skubitz (R). MICHIGAN

A SUSUAL, Gov. William G. Milliken (R), 55, has a tough race for relection in this Democra tic state. His opponent is aggressive state Sen. William B. Fitzgerald (D), 36, and the issues are Milliken's handling of the PBB chemical contamination of cattle feed and other controversies from his 10 years in Lansing. Milliken's popularity has him 8-10 points in front in the polls and he is favored to hold the lead.

Sen. Robert P. Griffin (R), 54, who announced retirement plans in 1977 and then changed his mind, is finding his indecision costly. His opponent, Carl Levin (D), 43, a former Detroit city council president, has filled the air with Griffin's 1977 statements about losing his zest for the job and has hammered hard at Griffin's uncharacteristic absenteeism following his retirement announcement. Griffin is behind in most polls, and, while the margin is narrow, he rates as the most theatened Senate incumbent in some private GOP scorecards.

Griffins's waffling could also cost the GOP a House seat. Rep. Philip E. Ruppe (R) wanted to be Griffin's successor and refused to run for the House again when Griffin changed his mind. The Republican is a slight favorite in the close race in Ruppe's old district, but a switch is possible. Also causing the GOP anxiety is the fate of Rep. Garry Brown (R), matched against the same Democrat he beat by less than 4,000 votes in 1976. MINNESOTA

EVEN THE GOPHERS are turned on by politics in Minnesota this year, which has provided more drama and suprises than only other state.

Gov. Rudy Perpich (D), 49, who inherited the office in the musical-chairs game following Walter F. Mondale's elevation to vice president, is showing more power than people expected against the challenge of Rep. Al Quie (R), 54, a respected 20-year veteran of the House. Perpich, a self-styled populist dentist from the Iron Range, is 9 points up in the latest Minneapolis Tribune poll, but Quie is pounding on the tax issue and figures to make it close.

Sen. Wendell Anderson (D), 45, was hit by a delayed backlash to his tactic of resigning as governor so Perpich could appoint him to the Mondale seat. At one point, polls had him 23 points behind Rudy Boschwitz (R), 47, the plywood millionaire and GOP national committeeman who began running for the seat the moment Anderson was appointed.

Anderson got caught in the backwash of the intraparty fighting over the second Senate seat, but now seems clear of that problem and is beginning to exploit traditional Democratic loyalties and issues and Boschwitz's shortcomings as a novice campaigner. Private polls are not as close as the Tribune report that Anderson is only 4 points behind, but the race is moving into the tossup category, with the momentum in Anderson's direction.

The second Senate race was created by the death of Hubert H. Humphrey (D) and the decision of his widow, Muriel, two years of his term. Rep. Donald M. Fraser (D) was endorsed for the seat, but lost a bitter primary to businessman and Humphrey protege Robert E. Short (D), 60.

Mondale is rallying union and party support behind Short, but many of Fraser's liberal backers will either sit on their hands or support David Durenberger (R), 44, a respected lawyer and political moderate making his first campaign. Durenberger trailed Short by 7 points in the post-primary Tribune poll, but is still gaining recognition, and in that race, too, the lead could well switch.

Quie's old House seat, although loyal to him, is politically marginal, and the Republicans are only slight favorites to hold it. Democrats would like to defeat Rep. Arian Stangeland (R), who won a Democratic seat in 1977 special election, but they admit Stangeland has entrenched himself effectively even against a strong challenger. MISSOURI

WITH THE state auditor's race, in which ex-Gov. Warren E. Hearnes (D) is attempting a political comeback, the only statewide contest, interest centers on two House districts. Freshman Reps. Robert A. Young (D) and E. Thomas Coleman (R) will both be hard-pressed but both are slight favorites. NEBRADKA

IN AN OTHERWISE' bleak year for Republicans, Rep. Charles Thone (R), 54, is providing some cheer by leading the governor's race over Lt. Gov. Gerald T. Wheland (D), 53. A Lincoln Journal and Star statewide poll last week gave Thone a 46-to-32 percent lead, but Democrats say Whelan can still make it close as he becomes better known.

The GOP will need to reclaim the governorship to make up for the embarrassment of losing the second Senate seat to a Democrat for the first time in Nebraska history. The poll says Gov. J. James Exon (D), 56, has a 65-to-19 point lead over Donald Shasteen (R), 49, an aide to retiring Sen. Carl T. Curtis (R). Shasteen took the nomination when no one else would run against the popular Exon, and his campaign has been a series of self-inflicted wounds. The race for Thone's old House seat is rated a tossup, which means there could be only one Republican - Rep. Virginia Smith (R) - in the five-member Nebraska delegation in Congress next year. NORTH DAKOTA

THE MESSAGE is succinct, but not suspenseful. with no race for senator or governor, Rep. Mark Andrews (R) is expected to defeat public service commissioner Bruce Hagen (D). It's that simple. OHIO

ONCE AGAIN, as often before, Democrats think they can beat Gov. James A. Rhodes (R), who has been governor for 12 of the last 16 years. And this time it may be true. Lt. Gov. Richard F. Celeste (D), 41, who has been campaigning for four years, has built a following in rural Republican areas to offset Rhodes' appeal to blacks and ethnics. The man issue is the financing of the state's often-closed schools, and the verdict is not clear on public reaction to the contrasting plans the two candidates have put forward. The race is regarded as too close to call, and while Rhodes usually finishes with a rush, polls this weekend by both the Akron Beacon-Journal and the Columbus Dispatch put Celeste 4 points ahead.

Despite Rhodes' problems, Republicans are optimistic about the chances of beating Reps. Charles J. Carney (D) and Thomas A. Luken (D), and are more hopeful about holding the seat of retiring Rep. Charles W. Whalen Jr. (R), where Democrats had been favored and still may prevail. The only threatened GOP incumbent is Rep. Samuel L. Devine (R) and he is given the edge. SOUTH DAKORA

THE STATE will have its third governor in a year, but no one knows yet who it will be. Gov. Richard F. Kneip (D) resigned to become ambassador to Singapore and was succeeded by Lt. Gov. Harvey Wollman (D), who promptly lost the primary to state Sen. Roger McKellips (D), 55. Now McKellips is in a very tight race with Atty. Gen. William J. Janklow (R), 38.

Less suspenseful is the race for the seat of retiring Sen. James Abourezk (D). Rep. Larry Pressler (R), 36, a jet-pro-pelled campaigner with a strong yen for the public attention the Senate provides, is far in front of former Rapid City mayor Don Barnett (D), 35, and Republicans count this as a sure pickup. Democrats are favored to take over Pressler's House seat, however,

WISCONSIN

LEE S. DREYFUS (R), 51, a gregarious, red-vested college president, has come off his upset primary victory over Rep. Robert W. Kasten Jr. (R), to emerge as a serious threat to Gov. Martin J. Schreiber (D), 39, who took over last year when Gov. Patrick J. Lucey (D) became ambassador to Mexico. A Milwaukee Journal poll in late September put Dreyfus 5 points ahead, and both parties now regard the race as a tossup.

Republicans are throwing a heavy challenge at Rep. Robert J. Cornell (D), a Catholic priest, and despite lingering disputes from a very close primary fight, the GOP is favored to retain Kasten's old House seat.