The Hill News

Sen. John McCain (R-Ariz.) on Friday bashed Rick Santorum on Twitter, calling his campaign “desperate” and “irresponsible.”

McCain, the 2008 GOP nominee who has endorsed Mitt Romney, criticized Santorum for comments he made suggesting that Republicans consider President Obama over Mitt Romney in a hypothetical general-election showdown.

Santorum says no difference b/w Romney & Obama â€" clear sign of desperate, irresponsible campaign

â€" John McCain (@SenJohnMcCain) March 23, 2012

Santorum made the remarks while campaigning Thursday in Texas, drawing heavy criticism from Romney and his allies.

“If they’re going to be a little different, we might as well stay with what we have instead of taking a risk of what may be the Etch A Sketch candidate for the future,” Santorum said.

Santorum has since backed away from the comments, saying in a statement Friday he would never vote for Obama, and “to suggest otherwise is preposterous.”

“I was simply making the point that there is a huge enthusiasm gap around Mitt Romney, and it’s easy to see why â€" Romney has sided with Obama on healthcare mandates, cap-and-trade, and the Wall Street bailouts,” Santorum said.

Friday on CNN, Santorum press secretary Alice Stewart said the candidate would back whomever the GOP nominee is.

“Rick has made it abundantly clear that once the nominee is chosen he will stand behind the nominee and do everyt! hing we can to replace Barack Obama,” she said.