Barack Obama's former rival Hillary Clinton on Saturday threw her support behind his vice presidential pick Joseph Biden, as Republican opponent John McCain skewered Obama's choice in a new campaign ad. In a statement released just hours after Obama's campaign announced his running mate, Clinton said Obama “has continued in the best traditions for the vice presidency by selecting an exceptionally strong, experienced leader and devoted public servant. “Senator Biden will be a purposeful and dynamic vice president who will help Senator Obama both win the presidency and govern this great country.” The 47-year-old Democratic White House hopeful confirmed that he was picking Biden, a 65-year-old six-term senator from Delaware, in an early-hours e-mail and text message sent out to millions of signed-up supporters. The choice may be more difficult to swallow for Hillary Clinton's most ardent supporters, especially after news leaked to the press that she had not even been vetted for the job. “There's no doubt that some people are going to view this as she is not being accorded respect,” James Carville, a Democratic strategist with close Clinton ties, told CNN on Friday. “It would be demeaning for someone with more experience to take a back seat,” said Robin Carlson, a fierce Hillary Clinton supporter, interviewed Saturday on Fox News. “We love Hillary and we love her commitment to the party,” said Carlson, but she added that her group is “committed to not voting for Obama.” Many media reports of Clinton's latest campaign appearances on behalf of Obama this week in Florida to have been tepid in their enthusiasm for her former rival. A Wall Street Journal/NBC poll published this week found that only 52 percent of the roughly 18 million people who voted for Clinton in the marathon Democratic primary duel had so far decided to vote for Obama in November. Twenty-one percent said they would vote for McCain, while 27 percent had not yet decided. One in three of the group said they found Obama “arrogant and cocky.” The choice of Biden, who was first elected to the Senate in 1972, indicates Obama was more interested in filling gaps in his foreign policy experience than in finding someone who could reinforce his message of bringing change to Washington. Biden's record includes outspoken opposition to US government support for South Africa's apartheid system in the 1980's, agitation from the Senate for stronger US intervention in the Balkans in the 1990s and close involvement with US policy on Iraq, Iran and Pakistan.