New Jersey Republican Governor Chris Christie, who endorsed Mitt Romney in October, said yesterday Gingrich humiliated the party when he was House speaker, citing Gingrich’s $300,000 payment to resolve allegations of giving misleading information in a 1997 ethics probe.

“He was run out of the speakership by his own party,” Christie said on NBC’s “Meet the Press” program. “This is a guy who has had a very difficult political career at times and has been an embarrassment to the party.”

Playing into those fears, former Pennsylvania U.S. Senator Rick Santorum called Gingrich a “high-risk ca“He ndidate” and said Romney is “no longer the inevitable” candidate to win the nomination.

Meanwhile still reeling from his stunning loss in South Carolina, Romney says he will release his 2010 tax returns Tuesday.

“We made a mistake in holding off as long as we did,” Romney admitted to Chris Wallace on Fox News Sunday.

“We’ll be putting our returns on the Internet. People can look through them,” he said.

Romney was on the defensive after losing the South Carolina primary by 12 points to Newt Gingrich.

In other political news,Gabrielle Giffords, who was propelled into the national spotlight after being shot by a mad man during an event at a Tucson grocery store in 2011, will step down from Congress this week. (Her announcement is below)

The Arizona Representative announced her decision in a video message posted on the Giffords For Congress website.

“I have my work to do on my recovery so to do what is best for Arizona I will step down this week,” she said, in clear but slightly broken speech. “I’m getting better. Everyday my spirit is high.”

In the two-minute video, Giffords thanks Arizona for its support and says that the country still has work to do.

“A lot has happened over the past year. We cannot change that. But I know on the issues we fought for we can change things for the better. Jobs, border security, veterans. We can do so much more by working together,” she said in the video.