Republican presidential candidate Marco Rubio defended his Senate voting record during Wednesday night’s primary debate and hit back at the “mainstream media” for singling him out.

The first-term Florida senator argued that home state paper The Sun-Sentinel called for his resignation over missed votes, but endorsed Democratic Sens. John Kerry and Barack Obama in their respective 2004 and 2008 White House bids, despite missing 60 to 70 percent of their Capitol Hill votes.

“I read that editorial today with great amusement,” Rubio said. “This is another example of the double-standardthat exists in this county between the mainstream media and conservatives.”

To a CNBC moderator’s suggestion that he slow down and do his Senate job, Rubio said, “This country is running out of time. We cannot afford to wait another four years. The time to actis now.”

The voting-record question also created a sharp exchange between Rubio and fellow GOP candidate former Florida Gov. Jeb Bush.

Rubio was purportedly a protégé of Bush, and both are trailing GOP front runners Donald Trump and Ben Carson in national polls and in Florida.

“When you signed up, it was a six-year term. You have to show up,” Bush said. “What is this, a French work week? ”

Rubio responded: “The only reason you’re doing it … is because we’re running for the same position, and someone has convinced you that attacking me is going to help you.”