McCain said the kind of attacks thrown between the GOP candidates are far worse than those lobbed between then-Sens. Barack ObamaBarack Hussein ObamaNRATV host says Obama owes Parkland students an apology over shooting Paltry wage gains, rising deficits two key tax reform concerns Throwing some cold water on all of the Korean summit optimism MORE (Ill.) and Hillary ClintonHillary Diane Rodham ClintonClinton takes swipe at 'false equivalency' in media coverage of 2016 election Former presidents, first ladies come together to honor Barbara Bush Romney: Parts of Comey book read 'too much like a novel’ MORE (N.Y.) in the 2008 Democratic primary. 

McCain recalled a widely discussed ad by the Clinton campaign questioning whether Obama would be ready to respond to a "3 a.m." emergency if he were elected president. 

"That was nothing compared to this. The worst you got then was, ‘What are you going to do if you get that phone call at 3 in morning?’ " McCain said. "Compare that to ‘Massachusetts liberal’ and “RomneyCare’... These people are not respectful."

McCain's comments came a day before Michigan's primary. Both Mitt Romney and Rick Santorum have been campaigning hard in the state over the last few days. 

The Santorum campaign began using a robocall urging Michigan Democrats to vote for the former Pennsylvania senator in the Michigan primary. In response, Romney said that Santorum had been using "dirty tricks" because his campaign is "desperate."