Sen. Marco Rubio, R-Fla., is believed to be a 2016 presidential candidate. He is one of eight bipartisan senators working on a 2013 immigration bill. Reuters

Mitt Romney is giving Pennsylvania voters a potential glimpse of the general election by campaigning with Sen. Marco Rubio of Florida, a popular young lawmaker who is widely considered to be on Romney's vice presidential short list.

The anti-incumbent, Tea Party-powered wave of 2010 election propelled Rubio to his Senate seat, and he has established himself as a rising star in the Republican party. While he has repeatedly disavowed any desire to become vice president, Rubio's joining Romney on the stump carries the same suggestion of a tryout as Romney's appearances alongside Rep. Paul Ryan of Wisconsin and Gov. Chris Christie of New Jersey.

Rubio has said he would rather focus on effecting change for the legislative process, although he further fueled the speculation when he misspoke at a forum last Thursday.

Three, four, five, six, seven years from now, if I do a good job as vice president -- I'm sorry, as senator -- I'll have the chance to do all sorts of things, Rubio said.

In addition to his credibility with Tea Party supporters, the fact that Rubio is the son of Cuban immigrants could help shore up Romney's glaring weakness among Latino voters. Romney told supporters last week that his struggle to appeal to Hispanics spells doom for us and echoed Rubio's call for a Republican DREAM Act, an alternative to a stalled piece of legislation, popular among Latino voters, that would extend citizenship to some young undocumented immigrants.

Still, a recent poll found that Romney's Hispanic support would be virtually unchanged if he selected a Latino figure such as Rubio, Gov. Susana Martinez of New Mexico or Gov. Brian Sandoval as a running mate. The poll found that Hispanic voters rank the economy, not immigration, as their preeminent concern.