PORTLAND, Ore. (AP) -- Oregon charter schools activist Rob Kremer has impeccable conservative bona fides.

He is the founder of the Conservative Majority Action Project, a group that backs bedrock Republicans running for the state Legislature. He provides the right-wing perspective on a local talk show, chimes in frequently to agitate for the GOP on local blogs, and writes a column for a right-leaning magazine.

And yet, this November, Kremer won't be voting for Oregon's only statewide elected Republican, U.S. Sen. Gordon Smith.

"There are a lot more votes to be gained than lost by doing what he is doing, but I am one he has lost," Kremer said. "I can't vote for someone who has taken some of the positions he has taken, and if no one speaks out a little bit, it is only going to get worse."

Kremer's talking about Smith's increasingly common tendency to side with Senate Democrats on key policy issues, from global warming to the war in Iraq to the universal health care plan authored by Smith's fellow Oregon senator, Democrat Ron Wyden.

Smith is an endangered species, the last Republican senator from the West Coast, and vulnerable despite his piles of campaign cash, thanks to Oregon's increasingly Democratic tilt.

Accordingly, in recent weeks, he's been burnishing his image as a moderate, even running an ad in populous, liberal Portland and Eugene in which he allies himself with Democratic presidential candidate Barack Obama, normally persona non grata in GOP circles.

In doing so, he's risking alienating some of the social and fiscal conservatives like Kremer, who are the base of the Oregon Republican Party — but stands to gain support from the legions of nonaffiliated voters whose votes will be crucial in his race against Democrat Jeff Merkley.

In an interview this past week with The Associated Press, Smith said he's not concerned that fed-up conservative voters — many of whom are not especially fired up about presidential candidate John McCain either — will simply sit out the 2008 election.

"I always depend on independents — and I depend on a lot of Democrats, and I hope all the Republicans," Smith said. He knows how to "tack into the wind," he added, pointing out that he won his Senate seat in 1996, the same year that Bill Clinton took Oregon in a landslide vote.

Still, there are signs that he is moving to shore up his base. In an ad that's running only in the comparatively more rural Bend and Medford television markets, Smith proclaims: "Some say, lock the land up and the people out. No way. Because no one loves the land more than the farmers, loggers and ranchers who care for it. I approved this message because what some call the rest of Oregon, we simply call home."

Some conservatives are pragmatic about Smith's carefully crafted campaign message, in which the word "Republican" rarely if ever appears.

"He is in a re-election campaign," said Tim Nashif, who heads the Oregon Family Council, a group that spearheaded the state's ban on gay marriage. "It makes perfectly good sense to me that he needs to say what he has done to appeal to Oregonians as a whole."

It's not as though true-blue Republicans will have many other choices, Nashif added. There is a Constitution Party candidate in the race, Dave Brownlow, but his profile is low.

Nashif is closely studying the voter registration numbers, which aren't pretty for Republicans. According to the Secretary of State's office, there were 869,010 registered Democrats in Oregon in May, the most recent month for which data is available, and just 671,304 registered Republicans. In May 2007, the gap was far smaller: then, there were only about 750,000 Democrats, to 690,000 Republicans.

Gail Atteberry, who heads Oregon Right to Life, the state's most influential anti-abortion group, has also seen the numbers. And while she said she was extremely disappointed by Smith's admiring reference to Obama in his ad — Obama, she said, is the most "pro-abortion radical in the Senate" — she said she's sticking with Smith.

"We know it is posturing," she said. "But I know his heart, where he stands on our issue, and I am confident that he will always remain true to that cause. For that reason, in spite of some of these other things, I am going to keep on keeping on with him."

Others are simply keeping mum on Smith's campaign-year decisions. June Hartley, a Republican National Committeewoman from Ontario who was a fervent supporter of Mitt Romney during his failed presidential bid, called the Smith-Obama ad "unusual" with a hint of disapproval in her voice before declining further comment.

And some are just fed up, said Ted Piccolo, who runs nwrepublican.com, a widely read GOP blog.

"People understand it is a campaign year, there might be some positions or votes that will frustrate you, but man, he has gone way, way out of his way to cozy up to the Democrats," Piccolo said. "I think the Smith people are going to take all Republicans for granted and just assume they will show up, and you can't assume that. Politics isn't a spreadsheet."

As for Kremer, he says Smith lost him when he sided with Democrats last month in support of a cap-and-trade system, which would cap greenhouse gas emissions. The bill ultimately failed, but Smith said at the time that the climate change legislation would have helped reduce reliance on oil from overseas, while stimulating renewable energy industry.

Kremer, though, said the bill would increase energy prices at a time when Oregon's gas prices are among the highest in the nation. It was, for him, the last straw.

"That is a complete betrayal of what any reasonable conservative should expect," Kremer said. "He's always been a reliable vote on taxes, but the cap and trade system is a monumental tax increase. So for him to betray that long-standing principle is enough to lose my vote."