Tuesday is primary day in the states of Kansas, Michigan and Missouri as the political winnowing process continues -- and several races are key for seat counters.

The Michigan Democratic primary race for the gubernatorial nomination pits Rep. David Bonior, who lost his seat to redistricting, against former Michigan Gov. James J. Blanchard and the state's Attorney General Jennifer Granholm.

Granholm, who would be the first woman governor of Michigan if she won, is far ahead in the polls but everyone expects the vote to be close. The winning Democrat will have to face Lt. Gov. Dick Posthumus in the fall, who is trailing behind all three Democratic candidates in the polls.

An eye is also on the Democratic matchup for Michigan's 15th Congressional District in another case where a seat was lost due to redistricting. Two veterans are slugging it out: John Dingell, first elected to Congress in 1955, is facing four-term Rep. Lynn Rivers.

Dingell inherited his seat from his father in 1955 at the age of 25. He is the longest serving member of the House of Representatives, earning the title of House dean. His last serious primary challenge through his lengthy career was in 1964.

But Rivers, a spunky single mom who began her political career on the school board after working her way through college and law school, is not about to give up without a fight.

On its face, a primary race will have all the ingredients of a political whopper: Rivers is a female "outsider" benefiting from the full support of feminists and the university intelligentsia who reside in her middle-class, economically and socially liberal district.

Dingell is a lifelong politician who has spent almost 50 years bringing home the bacon to a blue-collar middle-class district that is liberal on the economic issues, but more traditionally conservative on the social ones.

Rivers is avidly pro-choice. Dingell wholeheartedly supports gun rights. She's got the backing of the influential pro-woman Emily's List. He's got the support from the powerful labor unions in their newly combined district.

It has been a surprisingly heated campaign. A recent poll put the two at a one-point distance with Rivers leading.

Over in Missouri, appointed Sen. Jean Carnahan is running for the right to serve out the remaining four years of her late husband's term. Mel Carnahan died in a plane crash two years ago but his name was on the ballot and three weeks after his death he defeated John Ashcroft. His wife was appointed to fill his seat until another election could determine who would take it.

Sen. Carnahan is expected to win the Democratic nomination hands down -- but will likely face a tougher battle in the fall against former Republican Rep. Jim Talent. Talent was barely defeated in the open governor's race of 2000 to Bob Holden, who appointed Carnahan to her seat.

Democrats held an off camera briefing for reporters Monday in which they said polling indicates "the political atmosphere is undergoing a modest, but significant change" due to voters' support for Democratic positions on issues like retirement security, corporate responsibility, prescription drugs, HMO reform, and Social Security.

But Democrats are worried that the United States may take action against Iraq prior to the upcoming election in a so-called "October Surprise."

When asked if Democrats are worried about the Bush administration taking action against Saddam Hussein, a DNC source said, "You mean, when General Rove calls in the air strike in October?"

Democrats are concerned that most of Bush's policy is determined by his senior aide Karl Rove, who is also the Republican Party's White House campaign guru.

Democratic sources went on to say they hope the president would not use the war against terrorism in a political way but added, "the temptation will be strong."

Most political experts who have been studying the numbers believe that it would be very difficult for Democrats to retake the House in the fall, where Republicans lead by a seven-seat margin.

No one is yet taking bets on what might happen in the closely divided Senate, where Democrats rule by a one-vote margin.

Fox News' Brian Wilson and Kelley Beaucar Vlahos contributed to this report.