Sen. Barack Obama late Thursday reinstated more than 800 California Democrats who wanted to become his delegates at the national convention after blocking them from contention earlier this week.

Obama's initial purge angered Democrats around the state who volunteered on his behalf and planned to compete Sunday in local caucus meetings for his 107 California delegate spots in Denver.

They suggested the removal of so many grass-roots supporters ran counter to his reputation for appealing to those outside the political establishment. Many complained Thursday to his national headquarters in Illinois.

"There has been an extraordinary outpouring of grass-roots support for Senator Obama," wrote Obama campaign manager David Plouffe in an e-mail Thursday night to delegate applicants.

"In recognition of this tremendous enthusiasm, our campaign has asked the California Democratic Party to allow all persons who have filed to be a district delegate candidate for Senator Obama at the Democratic National Convention to participate in the caucuses this Sunday, April 13, 2008," Plouffe added.

By comparison, Sen. Hillary Rodham Clinton cut about three dozen out of 1,000 who applied to become her delegates, a significantly smaller proportion.

California Democratic Party spokesman Bob Mulholland confirmed that all Obama delegates who properly filed their paperwork – about 1,400 – are eligible to compete Sunday.

The machinations surrounding pledged delegate selection, an oft-ignored party procedure, highlight the anxiety both campaigns have in a presidential contest that remains undecided.

Clinton and Obama were expected to cut the applicant pool this week, but the size of Obama's purge caught many Democrats off guard. While Clinton officials eliminated people whose loyalties they felt were uncertain, Obama removed numerous longtime supporters. His campaign is now allowing all applicants, including those whose loyalties may have been in doubt, to compete Sunday.

State party Chairman Art Torres, in a statement, claimed some credit for Thursday's decision, which he applauded. But activists said they believe their pressure Thursday forced the Obama campaign to change its decision.

"I'm glad they did what they did, and hopefully we can get as many young people as possible elected as delegates," said California Young Democrats President Rocky Fernandez, an Obama applicant who was dropped.

The last-minute reversal also brought relief to volunteers like Ryan Loney, a second-year UC Davis student and campus coordinator for Obama. Loney worked in Philadelphia on Obama's behalf and received support from dozens of college students in his district before he found out the Illinois senator dropped him and others from delegate contention.

"I think that was a smart move on part of the campaign," Loney said. "I wish there would be more communication for what happened. … I'm going to get on my phone right now and say, 'Hey, let's get some carpools together, and we're going to Napa.' "

They learned of their fate only by checking a Web site Wednesday night, where lists of as many as 100 contenders in some districts had dropped to 20 with no explanation.

Obama spokesman Ben LaBolt declined comment, referring to Plouffe's e-mail as the official campaign statement. Mulholland suggested earlier that Obama's campaign may have been concerned about the logistics, and Plouffe referred to the potentially difficult size of Sunday's events.

"An overwhelming number of supporters have signed up to run for delegate, so there will likely be lines and tight space at the caucus locations," he wrote. "We ask for everyone's patience and cooperation."

All registered Democrats get to participate in caucus meetings Sunday in each congressional district to select delegates for Denver. These 241 pledged delegates, including 134 for Clinton, are expected to carry out the wishes of California voters in the Feb. 5 primary, won by Clinton. State party leaders will choose another 129 pledged delegates in May, spots largely dominated by donors and political insiders.