Republican Sen. Gordon H. Smith has compiled one of the most moderate voting records in the Senate during his two terms, but that may not be enough to win over voters in this increasingly "blue" state.
Recent polls show Mr. Smith, 56, slipping behind his Democratic challenger, state House Speaker Jeff Merkley, by a handful of percentage points as the bitter, contentious race enters its final stretch.
But analysts say the race has less to do with Mr. Smith and Mr. Merkley than with Mr. Bush and Mr. Obama. While Democratic presidential candidate Barack Obama is cruising to a double-digit win in Oregon, President Bush's approval rating hovers at 20 percent, the lowest in the nation.
"In Oregon, it's a very bad year to be a Republican," said pollster Tim Hibbitts of the Portland-based firm Davis Hibbitts and Midghall. "Bush is frankly dragging down the Republican candidates. I can't emphasize how much damage he has done to Republicans in this state."
The McCain campaign, having given up on the solidly Democratic state, hasn't helped matters.
"Obama is very strong here, and there's no McCain presence whatsoever," Mr. Hibbitts said.
As a result, Mr. Smith's record of bipartisan cooperation isn't resonating as loudly as he had hoped. Over the summer, he irked Democrats by running two television ads linking himself to Mr. Obama, pointing out that the two had backed legislation on gas-mileage standards.
"Gordon Smith is working with Barack Obama and most Democrat senators for a bipartisan energy bill," intoned one ad.
Mr. Merkley, 52, has shot back with ads linking his opponent to the president - "Smith votes with George Bush 90 percent of the time," says one - and more recently with campaign spots featuring Mr. Obama himself.
"With Jeff Merkley in the U.S. Senate, we can get our country back on track," the Illinois senator says.
Mr. Smith has since switched tactics by warning about the dangers of "one-party dominance" in the event that Mr. Obama wins the presidency and Democrats gain 60 seats in the Senate, enough for a filibuster-proof majority.
"We're trying to make the case to the people of Oregon that one-party dominance, a blank check, no checks and balances, could be a very unfortunate thing for our country," said Mr. Smith in a radio interview here Tuesday with conservative talk-show host Lars Larson. "That doesn't work, and Americans know that."
The Merkley campaign responded by accusing Mr. Smith of attempting to put the brakes on an Obama presidency.
"It's 180 degrees from where he started in this campaign," Merkley spokesman Matt Canter said. "In this, the final week, he's standing up for gridlock."
The Oregonian, the state's largest newspaper, endorsed Mr. Smith, praising his independence and calling him "no slave to the GOP agenda" and noting that "Merkley has thus far showed no inclination to express his independence from the liberal wing of the Democratic Party's line on anything of importance."
Mr. Smith supported the Bush tax cuts and a constitutional amendment against same-sex marriage. At the same time, he has worked with Democrats and broken with Republicans on key votes.
Despite his pro-life stance, he supported stem-cell research. He co-sponsored legislation with Sen. Edward M. Kennedy, Massachusetts Democrat, to expand hate-crimes protections to gays. He voted against drilling in the Arctic National Wildlife Refuge. He reversed his earlier support for the Iraq war and has since called for the removal of U.S. troops.
Mr. Smith has also worked closely with Oregon's senior senator, Democrat Ron Wyden, issuing joint press releases and holding town meetings together. The Republican cited his relationship with Mr. Wyden in early campaign ads, although Mr. Wyden has made it clear that he backs his fellow Democrat.