Sen. Marco Rubio Folded on Immigration Reform, Says Sen. Claire McCaskill

— -- Coming to the defense of former Secretary of State Hillary Clinton, Missouri Sen. Claire McCaskill took aim at recently declared Republican presidential candidate Marco Rubio, saying the Florida senator folded on immigration reform after coming under pressure from the conservative wing of his party.

"If you look at Marco Rubio's record, he took a principled, courageous stand on immigration reform and we passed a comprehensive bill in the Senate," she said. "Then, the minute his party's base started chewing on him about it, the minute Rush Limbaugh criticized him, he folded like a cheap shotgun."

The scathing critique came in response to Rubio’s dismissal of Clinton as "a leader from yesterday ... promising to take us back to yesterday."

McCaskill turned that comment around on the Florida senator, calling his immigration about-face "old-style politics."

"I don't think that he necessarily represents some generational change," she said.

McCaskill, who has emerged as a strong defender of Clinton’s presidential ambitions in recent months, chose President Barack Obama over the former first lady in the 2008 Democratic primary. When asked about that decision, the senator said she was "glad [she didn't] have that kind of tough choice this time."

McCaskill also repeatedly said Clinton does not need a challenger in the upcoming Democratic primary, despite a Bloomberg poll suggesting 72 percent of Democrats and independents want an internal debate.

"The way she's going about this campaign shows she's not interested in a coronation either," said McCaskill, referring to the grassroots campaign-style the Clinton team is projecting in Iowa.