National poll shows VP pick didn't improve GOP's presidential prospects A new poll shows that Republican presidential candidate Mitt Romney's pick for his running mate isn't helping to improve his chances overall . Generally, candidates can expect a nation-wide "bump" in polling following their vice presidential picks. In 2008, for instance, Barack Obama saw a jump in the number of voters who would be more likely to vote for him due to his pick of Joe Biden for vice president. 24 percent of Americans were more likely to vote for Obama due to the pick, as opposed to 16 percent who were less likely. Other picks had similar outcomes : Sarah Palin in 2008 (34 percent more likely vs. 25 percent less likely) John Edwards in 2004 (28 percent vs. 7 percent) Joe Lieberman in 2000 (20 percent vs. 7 percent) Dick Cheney in 2000 (16 percent more likely vs. 14 percent less likely) But polling for Mitt Romney following his pick of Rep. Paul Ryan (R-WI) shows that voters are...