If U.S. Rep. Joe Schwarz had won the Republican primary, the prospect of a Democratic upset in the 7th District wouldn't even be a longshot, analysts say.

Though Democrats are given a chance to win one or both houses of Congress amid a rash of Republican controversies -- including the sex scandal of former Florida U.S. Rep. Mark Foley -- Schwarz would have been expected to coast to victory Tuesday.

"Schwarz had a strong crossover appeal," notes Richard Czuba, president of the Glengariff Group, a Chicago-based polling outfit that has worked for Schwarz.

In the 2004 general election, the Battle Creek Republican won 58 percent of the vote against Sharon Renier, D-Munith.

Whom those 176,053 voters support could decide this year's contest.

Will they move to Schwarz's left and pick Renier, who is trying for the seat again? Or will they veer right and select Tim Walberg, who ousted Schwarz in a contentious GOP primary?

Call it the Schwarz factor.

"Those of you who voted for Joe Schwarz should feel welcome here," Gov. Jennifer Granholm said last week while stumping for Renier in Jackson . "Those bread-and-butter moderates ... have been left behind by the Republican Party."

It's no coincidence first lady Laura Bush stumped for Walberg on Thursday in Schwarz's hometown, Czuba said.

"The district is Republican," Michigan Republican Party spokes-woman Sarah Anderson said. "People will turn out for Tim Walberg."

Or will Schwarz supporters just stay home?

"Few people vote in the primary. People don't know who Tim Walberg is," said Ed Sarpolus, vice president of the Lansing-based polling firm EPIC/MRA. "And he's to the right of where the district is. But nobody knows Sharon Renier."

Schwarz says he has made up his mind -- and he won't vote for Walberg.

The congressman contended Walberg won the primary "by blatantly distorting my record and committing character assassination."

Schwarz's campaign last month filed an extensive campaign-finance complaint, contending Walberg illegally took more than $500,000 in contributions.

Schwarz also blasted his former foe for not backing "life-saving" embryonic stem-cell research and supporting intelligent design.

But the surgeon and former state senator has played coy about endorsing Renier or another candidate.

"Sharon is a woman of good character," Schwarz said. "As far as I can tell, her positions are fairly moderate."

In the 7th District, which President Bush carried in 2004 with 54 percent of the vote, the conventional wisdom is that a Democrat doesn't stand a chance.

But since the primary, Walberg's campaign has taken heat and fundraising has slowed. In October, a paid official resigned after the Citizen Patriot reported he pleaded guilty to domestic violence.

Renier lagged behind Walberg by 8 points in an uncommissioned poll released last month, with 22 percent undecided.

That puts the race closer than expected -- which could be evidence of the Schwarz effect. Schwarz and Renier won a combined 39,732 votes in the primary -- far more than Walberg's 33,245.

Renier is in a statistical dead heat with Walberg in Calhoun County , Czuba notes.

Schwarz backer Anne Noble said she'll likely vote for Renier.

"I honestly believe Walberg bought the election," the Jackson freelance writer said.

But other Schwarz supporters such as William Deary say they'll cast their lot with Walberg.

"I support the president and I support the party," said Deary, CEO of Jackson-based Great Lakes Home Health and Hospice.

In the end, Walberg remains the better-known candidate with more cash and friends in high places -- including the National Republican Congressional Committee and the Washington lobby Club for Growth.

Bolstered by a fundraiser by Vice President Dick Cheney, Walberg has pulled in more than $1 million and outspent Renier 26-to-1, Federal Election Commission reports show.

"We know that money usually wins," notes Rich Robinson, executive director of the Lansing-based Michigan Campaign Finance Network.

"It would truly be an upset if Walberg did not win."