Republican presidential candidate Jeb Bush pressed his attack on rival Marco Rubio's record of missed Senate votes, saying it showed Rubio had "given up" on breaking through the political gridlock in Washington.
Bush questioned whether Rubio, a U.S. senator from Florida, had shown the leadership skills or level of accomplishment needed to bridge partisan divides and solve longstanding problems.
"In this era of gridlock, it's really hard to break through, and I think he's given up. And I think that's the wrong thing to do," Bush, a former governor of Florida, said in an interview on NBC's "Meet the Press" that aired on Sunday.
"This is about public service, about solving problems," Bush said. "I can change the culture in Washington."
In one of the most notable exchanges in last week's Republican presidential debate, Bush criticized Rubio for missing Senate votes while campaigning and suggested he resign his seat. But Rubio punched back, accusing Bush of attacking him in an effort to right his struggling White House bid.
See photos from the Republican debate on CNBC:
Rubio responded again on CBS's "Face the Nation" on Sunday, saying beating Democratic frontrunner Hillary Clinton was more important than missing meaningless Senate votes.
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"The truth is, I don't like missing votes, but what I would really hate is to wake up on the first Wednesday of November to the news that Hillary Clinton's been elected president," Rubio said.
"Far too many votes today in the Senate are predetermined. We know what outcome's going to be. It's being done for messaging purposes, but it's never going to pass," he said.
Rubio's debate performance won praise and new momentum for a campaign that has been stuck in polls behind Republican frontrunners Donald Trump and Ben Carson.
Bush, meanwhile, has faced repeated questions since the debate about whether his White House bid can survive. He said that was part of the "tribulations" of a campaign.
"I have enough self-awareness to know that this is the bumpy time of a campaign," Bush said. "This is the process. I totally understand it, and I'm more than prepared to fight on."
Bush told NBC he had never seen a memo from his campaign that surfaced last week calling Rubio a "risky bet" for Republicans. But he said "comparing and contrasting" candidates is part of the political process.
Watch Bush's interview on 'Meet the Press' in full:
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