The best analyst of political polling data says Romney's V.P. pick means he knows he's losing.
Everyone knows political opinion polls tend to fluctuate weekly or daily. I try not not to put too much weight on any one poll result. If I want to get the best analysis of where the race for President stands, I've come to depend on Nate Silver's extremely accurate and focused poll analysis. My first reaction to Mitt Romney's pick to be his Vice Presidential runing mate was "he's desperate!" But my second reaction was to check out Nate's analysis to see if he agreed. He does:
"When a prudent candidate like Mitt Romney picks someone like Representative Paul D. Ryan of Wisconsin as his running mate, it suggests that he felt he held a losing position against President Obama. The theme that Mr. Romney’s campaign has emphasized for months and months — that the president has failed as an economic leader — may have persuaded 47 or 48 or 49 percent of voters to vote for him, he seems to have concluded. But not 50.1 percent of them, and not enough for Mr. Romney to secure 270 electoral votes."
To read the rest of the analysis, check out his blog, 538.