(CNN) -- Looks like they may be ready to bury the hatchet back at the Home Office.
Republican presidential nominee Sen. John McCain is slated to make an appearance on David Letterman's show Thursday, three weeks after he raised the ire of the generally mild-mannered host by canceling his scheduled appearance at the last minute, citing his decision to suspend his presidential campaign because of the financial crisis.
"This doesn't smell right," Letterman said then, during a routine that only half appeared to be a joke. "This is not the way a tested hero behaves. Somebody's putting something in his Metamucil."
Letterman didn't appear to buy the Arizona senator's explanation for the cancellation, showing the audience a live feed of McCain preparing for an interview with CBS anchor Katie Couric.
After praising McCain's record as a prisoner of war in Vietnam, he said, "This is not the John McCain I know, by God." Watch Showbiz Tonight talk about Letterman's rant »
"It makes me believe something is going haywire with the campaign," he said. "Something's gotten to him."
Letterman also took a dig at Republican VP candidate Sarah Palin.
"Here's what you do if you are running a campaign in the middle of an economic crisis and it's about to crater," Letterman continued.
"You go back to Washington, you handle what you need to handle. Don't suspend your campaign. You let your campaign go on shouldered by your vice presidential nominee ... or is that really a good thing to do? See what I am saying?"
Speaking on NBC's Today Show the next morning, McCain spokeswoman Nicole Wallace said, "We deeply regret offending Mr. Letterman, but our candidate's priority at this moment is to focus on this crisis," she said.
Letterman commiserated on air with Paris Hilton that he felt like an "ugly date."