Former President Clinton will hit the campaign trail Sunday in Michigan for Rep. Mark Schauer (D-Mich.), Rep. John Dingell (D-Mich.) and gubernatorial candidate Virg Bernero (D).

Dingell and Schauer both face tough challenges from Tea Party-backed candidates.

Dingell's race has gotten more competitive as the election gets closer. One of the possible factors: Michigan has the second highest unemployment rate among the 50 states.

Schauer, meanwhile, faces a difficult reelection battle against former GOP Rep. Tim Walberg (R), whom he defeated in 2008.

The Hill 2010 Midterm Election Poll from earlier this month showed Schauer and Walberg tied at 41 percent, but a recent Epic MRA poll showed Schauer with a 7-point lead over Walberg. 

The former president has been popular on the campaign trail this cycle, campaigning nationwide for vulnerable Democrats. Among the states at which he's made stops: Arkansas, California, Florida, Nevada, New York, Ohio, Pennsylvania and West Virginia. He is in Maryland on Thursday to help Democratic gubernatorial candidate Martin O'Malley.