Republican Presidential Candidate Rand Paul makes stop in Rochester

"We have to be conservative with all spending", whether for the military or domestically, Paul said. Want to go where the high-paying jobs don't pay that much, where - as Rand Paul suggests - you'd find more equality? Marco Rubio over his plans to increase the defense budget by $1 trillion over the next 10 years without explaining how he would pay for the increase. "How is it conservative to add a trillion dollar expenditure to the federal government?"

Polls have shown Paul struggling to break out of the crowded Republican field of candidates.

Rubio answered saying America must remain the strongest military power on Earth, contending "we can't even have an economy if we are not safe".

The heated exchange exposed the fault lines in the GOP as conservatives grapple with the world that seems increasingly in turmoil and a country weighed down by mounting debt.

Rubio: "We have to defend this nation".

The senator is hoping to appeal to Minnesota's libertarian streak: the same one his father Ron Paul captured in 2012, finishing second in Minnesota's precinct caucuses.

Peter Berkowitz, a senior fellow at the conservative Hoover Institution, described "a very hard balancing act" for Republicans between the instinct for fiscal restraint and the deep-rooted conservative tradition of a strong national defense.

"We have to decide what is conservative and what isn't conservative", Paul declared. "The better way to characterize the tradition is really an unending debate between these two sides".

The first 17 references made in the Milwaukee Theatre were done with particular emphasis by U.S. Sen. If you really support cutting spending, you have to cut across the board... Rand Paul could be seen walking toward the moderators. But now, a downsized military, the rise of ISIS, instability in the Middle East and a more aggressive Russian posture are making a strong defense a priority for most conservatives.

Bank of America's "Transforming World" Atlas. "We would want to know, we would want access to these people's phone records because it would give us clues as to who they were working with, who probably may be involved in plots themselves later on down the road", Rubio said.

"If you want to send troops over there, we don't send 50", Paul said. Next up was Cruz with 88,130 mentions, and then Paul, who got the most chatter of any debate so far with 73, 159 mentions.

"The antipathy toward Obama is so great", Ornstein said.

The Kentucky senator told a young audience Monday at the University of Minnesota to resist promises of free college and other government-driven programs as they size up 2016 candidates.

Paul's remarks appeared to resonate with the crowd that responded with subdued applause but stayed in their chairs for the duration of his 30-minute speech. That's a largely because views on foreign policy are in no way homogenous within the movement. Paul said he did not believe either Donald Trump or Ben Carson would be president, and he said that US foreign policy would be no different under Florida Sen. "I agree with Marco, I agree with Ted, we have no choice".