Fred Thompson, the 2008 presidential candidate and former U.S. senator from Tennessee, endorsed Newt Gingrich for the GOP nomination on Monday, two days after Gingrich's stunning upset over Mitt Romney in the South Carolina primary.

Newt Gingrich is the guy who can articulate what America is all about -- American exceptionalism -- who can make the case and not just read the talking points or do it off the teleprompter, Thompson told Fox News' Sean Hannity. He can make the case for free markets and our basic case that lower taxes can be good for everybody. Bring about growth, it's good for everybody. He is not afraid. He is tough. He is experienced.

Thompson's endorsement gives an added boost to a campaign that was declared dead on arrival before resurging dramatically -- not once, but twice.

The 2012 campaign has become, in many respects, a contest over who can be the most anti-Washington and anti-establishment -- many voters who supported Herman Cain saw his lack of political experience as a strength rather than a weakness -- but Thompson said that was the wrong way to look at it.

I don't think anymore [that] it's an advantage to be able to say, 'I know nothing about the operation of the federal government,' Thompson said.

He added that, as a longtime congressman and then as speaker of the House, Gingrich demonstrated his ability to effect change in Washington.

He conceived and carried out, really, a revolution in American politics at that time, he said, referring to the 1994 Contract with America, in which Gingrich helped sweep a Republican majority into Congress for the first time in decades. We were able to balance the budget for about four years in a row, pass welfare reform and begin to rebuild a depleted military. These things can be done, but we can't be apologetic about it or be tentative about it.

He did not address the increasingly widespread argument that, while Gingrich did a great job engineering the 1994 Republican takeover, he failed to lead as speaker of the House, and eventually resigned in 1998 amid near-rebellion from the Republican rank-and-file. He also did not address the fact that, of the four consecutive balanced budgets, only two were passed on Gingrich's watch.

Thompson did, however, criticize Gingrich's decision to campaign more negatively in recent weeks, in contrast to his earlier insistence that he would never attack a fellow Republican -- but he noted that the other candidates were guilty of that as well.

If these candidates want to spend their time talking about what happened 10, 15, 20 years ago and mistakes that were made in their personal lives or business lives or political lives, I'm sure that each candidate is going to have plenty to talk about, Thompson said. I think the American people are fed up with all of that. They are asking the question, who is going to be bold enough, smart enough, articulate enough ... to beat Barack Obama and start the difficult task of righting this American ship?

Whatever his faults, Gingrich will do all that, Thompson said.

I think we're at a tipping point in this country, he said. I think this president is taking us down the road of a genuine welfare state, full-fledged, even when we have the example of Europe to teach us and guide us.