A new Florida PPP poll investigated what effect selecting Rubio as VP would have on Romney’s chances in the state. They found that Romney would receive slightly less support with Rubio as his running mate than he otherwise would:

Rubio’s drawn the most attention as a potential Veep pick, but with him on the ticket Romney actually drops from 45% to 43% with Obama staying at 50%. There’s not much evidence Rubio would be able to draw Hispanic voters to Romney. In the straight Obama/Romney match Obama leads 52-37 with Hispanics and in the Obama/Biden v. Romney/Rubio match Obama still leads 52-37 with Hispanics. Rubio is not an overwhelmingly popular figure in Florida with 43% of voters approving of him to 41% who disapprove.

This agrees with much of what Rasmussen found when it polled Rubio’s favorability in Florida last month. According to Rasmussen, Rubio’s overall favorability among likely voters was 48%/41% (another 12% were not sure), but among Hispanics it was 16%/64%. If Rubio is viewed that unfavorably by likely Hispanic Floridian voters, there is no reason to think that he would help the presidential ticket with Hispanic voters elsewhere. More independents view him unfavorably (48%) than favorably (36%), and the same goes for moderates (33%/50%).