I expect these numbers to get worse in light of Paul Ryan's ties to the GOP Loser du Jour, Todd Akin. Via First Read:
According to the new NBC News/Wall Street Journal poll, 22 percent of registered voters say Mitt Romney's selection of Paul Ryan to be his running mate makes them more likely to vote for the presumptive Republican presidential nominee.
That's compared with 23 percent who say the Ryan pick makes them less likely to vote for Romney, and 54 percent who say the new running mate doesn’t affect their vote either way.
These numbers suggest the Ryan pick has had less of an impact on voters than previous running mates have had. [...]
In the poll’s feeling thermometer, moreover, Ryan’s favorable/unfavorable score stands at 33 percent/32 percent.
Independents are divided.