Gene J. Puskar/AP Photo

Arlen Specter didn't watch last night's GOP debate, but he definitely heard about it.

Having been out of the news for some time, the former senator from Pennsylvania was briefly mentioned on the stage in Arizona as Mitt Romney blamed his chief rival, Rick Santorum, for his 2004 endorsement of the senator who became a Democrat and voted for President Obama's signature health care plan that's so hated by conservatives.

Specter, a Democrat who became a Republican for decades before returning to the Democrats again just briefly, said Thursday that he's happy to take credit for "ObamaCare" - but that he doesn't understand why Romney mentioned him in the first place.

"There are a lot more important things to discuss than Arlen Specter," the former senator told ABC News. "I don't care if he brings me up. I just think there are more important things to do than talk about me."

Romney's line of attack was his way of turning around the health care argument that Santorum has used against the former governor - that the health program he signed into law in Massachusetts became a model for ObamaCare. Romney said last night that Santorum's endorsement of Specter in 2004, when they were both Republicans, is "the reason we have ObamaCare."

"If you had not supported him, if we had said 'no' to Arlen Specter, we would not have ObamaCare," Romney said. "So don't look at me. Take a look in the mirror."

Santorum defended his endorsement by saying that Specter told him in a "conversation" that if Santorum supported him, Specter would vote for President Bush's judicial nominees in his powerful role on the Senate Judiciary Committee. "He said, 'I'll support the president's nominees as chairman,' " Santorum told Romney.

But Specter, now an adjunct professor at the University of Pennsylvania's law school, said he "never" made a deal with Santorum. He said Santorum's defense wasn't appropriate though it was "equal to the attack" by Romney.

"I think in these debates, it's standard to disregard the relevant or important things and bring in the kitchen sink, anything that comes to mind," Specter said.