WASHINGTON -- Former President Bill Clinton and ex-Alaska Gov. Sarah Palin are lining up on opposite sides in West Virginia's Senate race, a key contest that could determine control of the Senate in the November election.

Clinton spent Monday in West Virginia, hoping to boost Democratic Gov. Joe Manchin's campaign as it struggles against wealthy Republican businessman John Raese. Meanwhile, former vice presidential candidate Palin announced she was backing Raese on her Facebook page, hoping to again demonstrate her political clout.

"He did every single thing you want Washington to do," Clinton said of Manchin during an event in Morgantown. If it weren't for the nation's economic struggles, Clinton said, Manchin would "be ahead by 30 points, and you know it."

But the economy is a mess and Manchin is in a tight race.

Manchin enjoys high popularity in the state and was assumed to have an easy route to the seat left open by Sen. Robert Byrd's death. But Raese has closed in, and strategists from both parties are now paying close attention to the race.

West Virginia hasn't sent a Republican to the Senate since 1958. Byrd, who died in June at age 92, held the seat for more than 50 years, but the Republicans and their allies are spending millions on ads trying to tie Manchin the Democratic-controlled White House and Congress.

"The last thing Washington, D.C., needs is another rubber-stamp vote for President Obama and the liberal agenda," Palin wrote, parroting Republican criticism of Manchin.

In a swipe at Senate Majority Leader Harry Reid and House Speaker Nancy Pelosi, Palin said: "John Raese has the courage and independence to stand up to the Washington politics of Reid and Pelosi. He'll do what's right for West Virginia."

She urged her supporters to back a slate of picks, including candidates in Virginia, Michigan and Arizona.

"A commonsense grass-roots movement is determined to get our country back to its founding principles and constitutional roots," Palin wrote. "I hope you'll join me in supporting a few more patriots this November -- because we need their voice and their votes in D.C."

Clinton is the last Democratic presidential candidate the state supported.

"I don't blame anybody for being mad. We've had a huge economic body blow," Clinton said. "But I'm old enough to know that if you make a decision when you're mad -- and this is not just politics -- there's about an 80 percent chance you're going to make a mistake."

Tuesday is the last day to register to vote in that state.