President Barack Obama is confronting a threat to his re-election as members of his base increasingly voice concern about his policies. Obama has faced a mini-rebellion from liberals after he went along with a decision to drop a public insurance option — and then its substitute, a “buy-in— expansion of Medicare — from the Senate health care bill. Liberals are also concerned about the climate change deal that he agreed to in Copenhagen and his decision to inject 30,000 additional troops into Afghanistan.But the White House has been taking steps to bandage the wounds.White House officials recognize that in order to be re-elected, Obama must maintain the passionate following of his most ardent backers, particularly liberals and African-Americans. These groups will not vote in any major way for Republicans, but Obama must try to replicate the enthusiasm that they exhibited in 2008 in order to get them to the polls in 2012.A recent poll by Research 2000 showed that a third of Democrats say a health care bill without a public option would make them less likely to vote in the 2010 elections.House progressives have voiced anger at the Senate health care bill and are concerned they spent too much time selling the idea to liberal constituents to back off easily.“We’re strung out with our base,— Rep. Raúl Grijalva (D-Ariz.) said.MoveOn.org, perhaps the leading activist Democratic group not controlled by the White House, has announced its strong opposition to the Senate measure. The group held a rally outside the White House earlier this month. And the White House has minced no words rebutting the outrage of former Democratic National Committee Chairman Howard Dean at the Senate bill and his insistence that it be scrapped.“I wouldn’t argue medicine with Dr. Dean — I would argue policy with him,— White House Press Secretary Robert Gibbs said during a briefing Dec. 15. Confronted the next day with fresh criticism from Dean, Gibbs turned up the heat. “Let me go through some of the things that I think Dr. Dean said on ‘Good Morning, America’ this morning that quite simply weren’t true,— Gibbs said. “Let me tell you what is good in the bill that is true that Dr. Dean forgot to tell people about this morning,— he continued. “I think if you talk to Members of the Senate that represent a similar viewpoint in the political spectrum that Howard Dean does, they seem to disagree as much with Howard Dean as I think we would.—Dean’s advocacy represents a particular threat to Obama, since he has a proven record of rallying liberals. During Dean’s bid for the Democratic presidential nomination in 2004, he and his political guru, Joe Trippi, arguably invented the type of mass, Internet-based campaign that Obama perfected in 2008. The president and his aides are also moving to ensure that the activists who made up his own populist campaign organization — called Obama for America in 2008 and now housed in the DNC under the banner Organizing for America — do not stray from the fold. Just two days after Sen. Ben Nelson (D-Neb.) sealed the Senate health care bill’s eventual passage by announcing on Dec. 19 that he would become the 60th Senator to back it, Obama fired off an e-mail to OFA members assuring them that this was the kind of legislation that they had worked hard to help him pass.“These are not small changes. These are big changes,— he insisted in a line that was bolded in the e-mail.“They’re fundamental reforms,— the message continued. “They will save money. They will save lives. And your passion, your work, your organizing helped make all of this possible.—The next day, former campaign chairman David Plouffe, who continues to be the force behind OFA, was himself messaging OFA inboxes with cheerleading for the Senate legislation, urging OFA members to help gin up support for its final passage.“This bill represents the most significant health reform our nation has seen since the creation of Medicare,— Plouffe declared. “We wouldn’t be this close to enacting these powerful reforms without all your hard work.—White House officials insist they are not taking the base for granted, as some House liberals have charged. “I’ve never heard the president say, ‘Oh, I don’t have to worry about that because these people are going to be with me,’— Gibbs said in response to a suggestion that Obama wasn’t worried about his base. “I’ve been with the president for six years and I’ve never heard him say something as silly as that.—