By William Yardley

updated 10:24 p.m. ET July 12, 2008

PORTLAND, Ore. - In the breathless weeks before the Oregon presidential primary in May, Martha Shade did what thousands of other people here did: she registered as a Democrat so she could vote for Senator Barack Obama.

Now, however, after critics have accused Mr. Obama of shifting positions on issues like the war in Iraq, the Bush administration’s program of wiretapping without warrants, gun control and the death penalty — all in what some view as a shameless play to a general election audience — Ms. Shade said she planned to switch back to the Green Party.

“I’m disgusted with him,” said Ms. Shade, an artist. “I can’t even listen to him anymore. He had such an opportunity, but all this ‘audacity of hope’ stuff, it’s blah, blah, blah. For all the independents he’s going to gain, he’s going to lose a lot of progressives.”

Of course, that depends on how you define progressives.

As Ms. Shade herself noted, while alarm may be spreading among some Obama supporters, whether left-wing bloggers or purists holding Mr. Obama’s feet to the fire on one issue or another, the reaction among others has been less than outrage.

For all the idealism and talk of transformation that Mr. Obama has brought to the Democratic Party — he managed to draw a crowd of more than 70,000 here in May — there is also a wide streak of pragmatism, even among many grass-roots activists, in a party long vexed by factionalism.

“We’re frustrated by it, but we understand,” said Mollie Ruskin, 22, who grew up in Baltimore and is spending the summer here as a fellow with Politicorps, a program run by the Bus Project, a local nonprofit that trains young people to campaign for progressive candidates. “He’s doing it so he can get into office and do the things he believes in.”

Nate Gulley, 23, who grew up in Cleveland and is also here as a Politicorps fellow, said too much was being made of Mr. Obama’s every move.

“It’s important not to get swept up in ‘Is Obama posturing?’ ” Mr. Gulley said. “It’s self-evident that he’s a different kind of candidate.”

Bob Fertik, president of Democrats.com, a progressive Web site, started asking his readers last month to pledge money to an escrow fund for Mr. Obama, as opposed to contributing to him outright. The idea was to make Mr. Obama rethink his decision to support the Bush administration’s wiretapping measure.

Mr. Obama initially said he would try to filibuster a vote, but on Wednesday he was among 69 senators who voted for the measure, which to many liberals represents a flagrant abuse of privacy rights. The legislation grants legal immunity to telecommunications companies that cooperated with the wiretapping program.

So far, 675 people have pledged $101,375 to Mr. Fertik’s escrow fund, money that theoretically would be donated to Mr. Obama once he showed a firm commitment to progressive values, Mr. Fertik said.

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But Mr. Fertik also said that while Mr. Obama’s change on the spying issue upset some supporters, it was not necessarily emblematic of a troubling shift to the center. He said he continued to support the senator, though he added, “We don’t see the need to close our eyes and hold our noses until November.”

Still, others warned that Mr. Obama risked being viewed as someone who parses positions without taking a principled stand.

“I’m not saying we’re there yet, but that’s the danger,” said David Sirota, a liberal political analyst and author. “I don’t think there’s disillusion. I think there’s an education process that takes place, and that’s a good thing. He is a transformative politician, but he is still a politician.”

Joe McCraw, 27, a video engineer from San Carlos, Calif., who writes three liberal blogs, said Mr. Obama’s shift on the domestic spying measure was a watershed moment.

“This is the first time I’ve ever seen him lie to us, and it makes me feel disappointed,” Mr. McCraw said. “I thought he was going to stand up there, stand by his campaign promises like he said he would, and it turns out he’s another politician.”

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