-- Barack Obama is facing a rebellion from the liberal blogosphere that helped him lock up the Democratic presidential nomination.
In recent days, Obama has criticized the Supreme Court for saying that child rapists cannot be executed and refused to oppose a decision knocking down a handgun ban. He announced a plan to support "faith-based" social work and said he would vote for a bill giving immunity to telephone companies that allowed warrantless wiretapping of their customers.
Those centrist positions may help woo swing voters, but they infuriated some of Obama's core supporters. Nearly 12,000 of them have formed an online group on Obama's presidential campaign website, urging him to vote against the domestic wiretapping bill.
"When a candidate decides to move to the center, he shouldn't move away from us," said Mike Stark, a University of Virginia law student who started the online mutiny.
Democratic blogs are flaying Obama's plan to vote for the wiretapping bill, said Markos Moulitsas Zuniga, founder of a leading liberal blog, Daily Kos. He's withholding a planned donation to Obama as a result.
"It's sort of a defining issue right now. It's huge," he said.
Moving to the political center is a common strategy in a general election campaign: candidates try to appeal to swing voters by moderating their more partisan primary stances.
Moulitsas said Obama's critics will still support him in November.
While Lee Miringoff, director of the Marist Poll, agrees that "his base is not going to flee," he warns that Obama runs a risk "anytime he moves from new-style politics. .. to something that has a scent of old school politics."
Arianna Huffington, founder of the liberal blog The Huffington Post, said Obama's centrist moves won't work — just as they didn't for John Kerry in 2004. Instead, she said, Obama should continue to try to draw in new voters as he did in the primaries. "This is the winning strategy for him: to appeal to the 83 million people who did not vote in '04."
Obama, rated last year as the most liberal senator by the non-partisan National Journal magazine, said he supports the domestic wiretapping bill because it is "a compromise that, while far from perfect, is a marked improvement" over a previous version. His aides insist Obama is not tempering his positions.
"Over the course of his career, Barack Obama has made decisions not on party or politics, but on what he thinks is best for America," spokesman Hari Sevugan says.
Some political strategists, however, note Obama is making a calculated shift to win over voters in a country where neither major party claims a majority.
"His supporters should understand this," said Emory University political scientist Merle Black. "He needs to reach out."
Democratic pollster Celinda Lake doesn't think there's any political risk for Obama. "The progressive voters really dislike John McCain," she said. "That should keep them on board."
Sen. Bernie Sanders, a Vermont independent who votes with Democrats and considers himself a Socialist, didn't deny that he sensed a shift in Obama's tone, but refused to criticize his colleague, whom he is supporting "enthusiastically."
Still, Sanders offered advice to Obama's critics.
"They should be organizing a grassroots movement," he said, "so it will be easier for Obama to stand up to the wealthy and powerful special interests who are going to be pushing him the other way."
Contributing: Jill Lawrence