By Marie Horrigan, CQ Staff

A tossup race this year seemed like a strong possibility for eight-term Michigan Republican Rep. Joe Knollenberg . He survived a close 2006 contest in suburban Detroit’s 9th District, which is closely divided between the two major parties. The Democrats’ challenge to freshman Republican Tim Walberg looked like more of a long-shot, if only because GOP voting habits are generally strong in the south-central 7th District he represents.

But as both contests head into the home stretch, the outcomes appear highly uncertain, prompting CQ Politics to change its rating on each to No Clear Favorite from Leans Republican.

There are two common threads between these races, the only two in Michigan’s 15 districts that are rated as competitive. Both Republicans survived unexpectedly close races in 2006 over little-known Democratic opponents, with Knollenberg winning by a career-low 5 percentage-point margin and Walberg winning by just 4 points. And these close shaves drew top-tier Democratic recruits in this year’s contests, with Walberg facing Mark Schauer, the minority leader in the state Senate, and Knollenberg battling Gary Peters, a former state senator who is a familiar figure in the 9th District.

In both contests, the most recent polling indicated the Democratic challengers were essentially tied with the Republican incumbents. Surveys on the congressional races taken before both parties’ political conventions about a month ago, conducted by the Lansing-based EPIC-MRA, indicated that Schauer was within the margin of error against Walberg, 43 percent to 40 percent, in the 7th District. In the 9th District, Knollenberg led former state Sen. Gary Peters 43 percent to 36 percent, but Peters took the lead (43 percent to 39 percent) once pollsters outlined the two men’s biographies, including their ages. Peters is 49 years old while Knollenberg is 75.

But it was the 7th District contest that took a particularly significant twist this week when former one-term Republican Rep. Joe Schwarz — whom Walberg unseated in a close and rancerous 2006 primary campaign — crossed over and endorsed Schauer to defeat Walberg.

Schwarz, who served a long tenure in the state Senate before his two years in the U.S. House, described Schauer as a protege of sorts. But he said he told Schauer he would stay out of the race unless there was an intervention by the Club for Growth, a conservative political action organization that heavily backed the conservative Walberg in the 2006 primary campaign and branded the more moderate Schwarz as a RINO, for Republican in Name Only.

“I take offense at what Club for Growth does in congressional elections,” said Schwarz, who got his cue to jump into the House race on Tuesday when the Club for Growth announced a $175,000 TV ad buy in the Lansing media market for an ad that charges Schauer is “crazy about taxes”. Schwarz almost immediately signaled his intention to endorse Schauer and made it official late Wednesday.

Schwarz told CQ Politics the endorsement was not part of a “quid pro quo” in retaliation for the Club for Growth’s involvement in his own primary loss in 2006, nor was it a personal attack on Walberg. “I have no personal animus toward Congressman Walberg. To me this is an issue of principle. Club for Growth does not belong in this congressional race, and the way that they come into congressional races and the things that they do and say distort a race,” Schwarz said. He would not speculate on what effect his endorsement would have on the race.

In a statement, Schauer said Schwarz was “a colleague and a partner in helping move our state forward for many years, and it is an honor to have his support in this campaign.”

Justin Roebuck, Walberg’s campaign manager, said the incumbent’s camp was “not particularly surprised at all” by Schwarz’s endorsement, but said that the race would remain centered on Walberg’s stands on issues, including lowering taxes in an effort to add Michigan jobs and improve the state’s struggling economy. “We believe the issues are on our side, but we’re not going to take anything for granted,” Roebuck said.

Schauer also is receiving plenty of help from his own side, as the Democratic Congressional Campaign Committee, his party’s House campaign unit, has put $61,000 into independent expenditures in the 7th District over the past week. Independent expenditures can promote one candidate and criticize the other, though these activities cannot under law be coordinated with a candidate’s own campaign.

One potential obstacle to Schauer is the decision by fellow Democrat and primary rival Sharon Renier to join the November contest as an independent write-in candidate. Renier, an organic farmer, was the 2006 Democratic nominee who came close to upsetting Walberg despite spending just $56,000 on her entire campaign. Nonetheless, the party establishment rallied this year behind Schauer, who defeated Renier in the Aug. 5 Democratic primary by roughly 2-to-1.

Renier said Schwarz’s endorsement of Schauer was “weird,” adding, “It’s like this personal vendetta to beat the Club for Growth.” But she continued that she did not think it would boost Schauer’s chances in the election. “The people pretty much got his number,” Renier said of Schauer, adding that he “hasn’t done anything for his 12 years of service except for take a paycheck.”