America's political Joe Six Pack has gone flat in advance of his only vice presidential debate with GOP challenger Rep. Paul Ryan.

A new Pew Research Center poll finds that registered voters view Vice President Joe Biden less favorably than Ryan--and much worse than they did when he debated the 2008 GOP vice presidential running mate Sarah Palin.

Worse, said Pew, voters by a 40 percent to 34 percent margin, expect Ryan to beat Biden at their Thursday debate. Independent voters, by a huge 42 percent to 25 percent, are putting their money on a Ryan win.

The poll is something of a downer for Biden, the president's cheerleader-in-chief. Just 39 percent of registered voters view him favorably while 51 percent have an unfavorable opinion of him. Back when he was running against Palin, his favorable rating was 53 percent and Palin's 51 percent.