Sen. Marco Rubio argued that the nation's immigration laws need to be overhauled and said that Hillary Clinton would be a flawed candidate for president.
"I just think she's a 20th century candidate," he said. "I think she does not offer an agenda for moving America forward in the 21st century, at least not up till now."
The Florida Republican made his comments in the second half of a two-part interview with Morning Edition host Steve Inskeep on Tuesday. Rubio also said he will make a decision about whether to run for president himself sometime within the next few months.
Rubio's very early status as a presidential front-runner on the GOP side was damaged by his decision to co-sponsor a comprehensive immigration bill that passed the Senate last year but ended up dead on arrival in the House.
Rubio told Inskeep its political failure came about because his fellow senators did not heed his own warnings to impose border security measures strict enough to satisfy House Republicans.
Rubio said that for major legislation to pass "any time in the next decade," immigration problems will have to be tackled in steps: first, greater border security, then modernizing the legal immigration system. Only after those goals are accomplished will the country be able to decide "what to do with the 11 or 12 million human beings that are in this country illegally," he said.
Rubio expressed sympathy for the children now fleeing violence in Central America but said the U.S. cannot address the crisis on its own, calling on help from hemispheric partners.
"We are deeply compassionate," he said. "This country's always had a place for people who seek asylum from conditions, whether they be political or otherwise.
"The problem is, it has to be through a process," Rubio continued. "This nation no nation is capable of sustaining or absorbing mass migrations."
Rubio said that even the law regarding Cuban immigrants needs to be modernized in order to reflect changing times. He'd like to see more migrants granted legal status based on job skills, as opposed to giving preference more often to those who have family ties or who are seeking asylum.
"I fully recognize that's how my parents came in 1956, but the country and the economy is fundamentally different than it was 60 years ago," he said, "and our immigration laws have to reflect this."
His party has struggled to attract support from Hispanics, but Rubio said an immigration overhaul, while it might help the GOP open up a conversation with Hispanic voters, would not be a panacea.
"I never did it for politics," he said of his own involvement in crafting immigration legislation. "I don't see a political upside, in the immediate term, for sure."
In terms of his political opponents, Rubio said Hillary Clinton is "extremely vulnerable on her record.
"The truth of the matter is she was the secretary of state during an administration that has had virtually no successes on foreign policy," he said.
Rubio, who is 43, said his continuing career in public service is motivated by the nation being at a "generational, transformational crossroads." He dismissed Clinton as being on the wrong side of those particular tracks.
Rubio said he'd make up his mind about running for president by early 2015.
"There's a lot of work to be done if you're going to run for president, or if you're going to run for re-election in a state as big as Florida," Rubio said.
Rubio discussed economic opportunity and his preference for limited government in the first part of his Morning Edition interview on Monday.