Marco Rubio and Kendrick Meek Pile on Charlie Crist

The second half of the debate between the three leading U.S. Senate candidates opened with more fireworks as Republican front-runner Marco Rubio took aim at his nearest rival, Gov. Charlie Crist, who is running without party affiliation.

Crist was under fire from two sides. Democrat U.S. Rep. Kendrick Meek opened the second half of the debate blasting Rubio for his record as speaker of the Florida House and attacking Crist for having no political beliefs -- flopping on issue after issue, including abortion. Meek said Crist was driven by political calculations since he needed Democratic votes to win.

Rubio, who had essentially ignored the governor in the first half of the debate, then jumped on Crist.

I do think its curious that he attacks me for backing positions he supported six months ago when he was running in the Republican primary, said Rubio.

Noting Rubio said he was not open to compromising on tax cuts, Crist said the right-wing Republican was so ideologically motivated that he would reject extending the cuts for 98 percent of Americans.