Romney hosts Rubio in Pennsylvania in coy VP audition CHESTER TOWNSHIP, PA -- Florida Sen. Marco Rubio displayed flashes of the personal intensity and articulate conservatism issues that have prompted hopes that Romney would select Rubio as his running mate during a joint appearance between the two men on Monday. At his first joint appearance with the presumptive nominee since endorsing Romney last month, Rubio acted to bolster Romney in a way to underscore speculation about his role on the Republican ticket this fall. Declaring Rubio an "extraordinary leader" before a crowd of more than 700 here in this Philadelphia suburb, Romney joined with Rubio for what more or less amounted to a vice presidential audition, though neither Romney or Rubio were eager to comment on those prospects at a press conference and subsequent town hall meeting. "The process for selecting a vice presidential running mate is just beginning," Romney told assembled reporters at a press conference, his first since March 16th. We're looking at various legal resources to help with in that process, accounting staff and so forth to take a look at tax returns and things of that nature. For his part, Rubio, a freshman senator, refused to comment altogether on his qualifications for the number two job. "I'm not talking about that process anymore," Rubio said in response to a question about whether he was experienced enough to become Romney's vice presidential nominee. But if he was cool to questions about his potential role in a future Romney administration, Rubio showed fire on the stump as he fielded questions from voters alongside Romney, frequently doubling down on Romney's policy positions. After Romney told his audience it would be "simply unacceptable for Iran to get a nuclear weapon," Rubio took the mic and went further, calling the possibility of Iran getting a weapon "so horrifying" that "there is no cost too high to bear to prevent that from happening." The son of Cuban immigrants, Rubio also made reference to his own personal history in response to a question about the role of entitlements and government in society, praising his parents and the American values they instilled in him. Why am I here today with you? Why did I get to serve in the United States senate? Why have I been privileged to have opportunities they didn't? It isn't because I worked harder than they did. It isn't because I'm smarter than they were. Its because I had something they didn't: the privilege and honor of being born in the single greatest society in all of human history," Rubio said, drawing loud applause from a crowd that seemed to hang on his every word. And while Rubio's fire, and humor (He joked about his wife telling him to buy an exercise bike because he was beginning to look "too senatorial.") provided a compelling contrast with Romney's cooler persona, the two appeared to lack some of the personal chemistry that was obvious between Romney and Rep. Paul Ryan, another likely candidate to join the vice presidential short list, as they campaigned together earlier this month in Wisconsin. At least one vital policy issue hangs in the air between the two men: Rubio's Republican answer to the immigration reform DREAM Act, which Romney told reporters he intended to study further, but upon which the took no firm position. Romney said he was likely to roll out his own, more comprehensive, set of immigration policy proposals closer to the fall election. You know I anticipate before the November election we'll be laying out whole series of policies that relate to immigration and obviously our first priority is to secure the border, and yet we also have very substantial visa programs in this country. I've spoken about the need to have a visa system that's right-sized for the needs of our employment community," Romney said. And so how we adjust our visa program to make it fit the needs of our country is something I'll be speaking about down the road.