“He wants to put out a whole bunch of negative ads? Go ahead. I hope that he will acknowledge at some point that I couldn’t care less," Christie added.
Christie continued going after Rubio, saying he has "never been in a tough race in his life" and attacking the Florida senator over his efforts on immigration in the Senate in 2013.
The pushback comes after the super PAC supporting Rubio began airing a pair of blistering attack ads targeting Christie over high taxes, low job growth, Common Core education standards and "scandals."
The ads are playing in New Hampshire, where Christie and Rubio are among several candidates vying for positioning before its first-in-the-nation primaries on Feb. 9.
Christie has gained some momentum recently in polls in the Granite State, where former Florida Gov. Jeb Bush and Ohio Gov. John Kasich are also battling behind Donald Trump.
Referencing the super PAC ads, Rubio later told reporters at a campaign stop in Iowa that "there's nothing in them that's inaccurate," according to the Post.
“I guess the point is something I would say too, and that is that this country cannot afford a president that’s not going to reverse the direction Barack Obama’s taken our country. We can’t have another president that supports Common Core or gun control or expanding Obamacare," Rubio said.