REEDSPORT, Oregon (CNN) -- For Republican Oregon Sen. Gordon Smith, his own party -- not his opponent -- may be his biggest obstacle to re-election this year.
Smith is a moderate Republican in a traditionally Democratic state, and the two-term senator is neck-and-neck with his Democratic challenger, Jeff Merkley, the speaker of the Oregon House.
Polls show that Merkley has a slight lead. A Portland Tribune poll conducted October 25-26 showed the Democrat leading Smith 45 percent to 40 percent.
With an unpopular Republican president in the White House and the downturn in the economy on voters' minds, Smith is criss-crossing the state to campaign on his bipartisan record.
"I've worked with Barack Obama on fuel efficiency for cars, John Kerry on housing, Ted Kennedy on civil rights and obviously when you want to get something done," Smith said. "It takes a common sense center in the U.S. Senate that's where I've been, and that's where I'll be."
Smith has also accused his Democratic opponent of wanting to raise taxes.
"Let's be real clear about one thing: I trust you with your money; he doesn't," Smith told voters in Coos Bay, Oregon. "Every one of you pays lower federal taxes because of how I voted. Every one of you pays higher state taxes because of the way he's voted."
With the chance that Senate Democrats could win enough seats across the country to reach a 60-seat, filibuster-proof majority, both national parties are pouring millions of dollars into TV ads into the state.
And running hard toward the center, one ad paid for by Smith's campaign even highlights his work with the Democratic presidential nominee.
"Who says Gordon Smith led the fight for better gas mileage and a better environment? Barack Obama," the Smith ad's narrator says.
Smith identified so strongly with Obama that Obama taped his first TV ad for another candidate, reiterating his support for Jeff Merkley.
Obama's Oregon campaign says, "it's important that Oregonians know who Barack is supporting."
Merkley is firing back at Smith, reminding voters at every turn of Smith's party ties. He's also criticizing Smith's record, including his initial support of the war in Iraq, although Smith later changed his position and broke with the White House.
"Gordon Smith, when he's here in Oregon, he talks about bipartisanship, but when he's in Washington, he votes like President Bush," Merkley said.
The Democratic Senatorial Campaign Committee has also targeted Smith, highlighting his ties with President Bush.
"After 2,846 days together, it's time to replace Gordon Smith, too," says the narrator in one ad, referring to the number of days Smith and Bush have both been in office together.
Political analysts say Merkley's message seems to be sticking with some voters.
"While I do believe Gordon Smith has a lot to offer and has offered a lot of Oregon, I do believe it's time for a change," said Brittney Hague, a waitress in a coffee shop in Reedsport.
But other voters are not ready to abandon Smith.
"Change is good. I can't dispute that," said Mike Macho of Reedsport, a registered Democrat. "But sometimes, you go with the guy with the most experience, you know, as long as he's doing a good job."
With just days before Election Day, the contest remains a toss-up. Given the state's late time zone, all eyes could be on Oregon, as the tight race could determine the balance of power in the Senate.
CNN's Chris Lawrence contributed to this report.