In 2006, the anti-Republican tide, fueled by frustration and opposition to the occupation of Iraq, even carried away Republican U.S. Senators who opposed the war. The most notable victim was Lincoln Chafee of Rhode Island.

Republican senators running in 2008 were well aware of this. Would 2008 bring a similar nationwide anti-Republican mood among voters?

With the demise of Iraq as the #1 issue among voters by the end of 2007, the danger receded. Iraq was replaced by the economy as the #1 issue, but the concern among voters was a general unease, not anger about any particular part of the slowing U.S. economic situation.

In Oregon, Gordon Smith’s reelection campaign perked along. His lesser-known opponent, Jeff Merkley, faced a real uphill struggle common among challengers to longtime incumbents—how to introduce oneself to voters, then how to make the argument that the challenger provides a strong enough reason to replace the incumbent.

Over the past two months, the campaign has turned to mudslinging, but the dynamic has stayed the same. A well known Republican incumbent against a less well known Democratic challenger. Even with all the outside interest groups throwing money into the race, Smith maintained a consistent 4–10% lead in polls since the May primary. There was one poll that showed a tied race in July, but it turned out to be an outlier—the pattern of Smith leading reasserted itself.

That has changed dramatically in the past 10 days. Two polls have shown a dead even race, and one shows Merkley leading by 4 points. The Smith incumbency is under real pressure.

Why?

It’s not the ads. They have not really changed over time, and we have not seen responses to them in previous polls.

What appears to have changed is the “tide” of voter sentiment. Instead of Iraq, as in 2006, the sweep of the economic crisis of the last half of September seems to be contributing to a growing anti-Republican wave. Looking back at elections over the past 100 years, when the economy takes a big hit, voters blame the incumbent president and his party. Note that in this analysis, the quality of the challenger is almost irrelevant. The key issue is the party of the president and the party of the incumbent.

It’s not only Gordon Smith who could be in trouble. In North Carolina Elizabeth Dole has experience the same rapid change—tied or behind in polls in the past 10 days after leading for months.

Moderate Republican Susan Collins of Maine still has a pretty consistent lead over her Democratic challenger—there was a bit of a narrowing in the past 10 days, but not enough to be a threat to Collins’s releection—we’ll wait to see if that holds.

There could be problems with the polls, this could be a short term issue while the bailout is being debated, it could be that all those independent expenditure ads are finally making a dent in Gordon Smith’s incumbency armor.

But whatever it is, Gordon Smith looks like he is entering the final phase of yet another fight for his political life. Those few scheduled debates between Merkley and Smith look more and more important every day.