ORLANDO, Fla. -- Former Sen. Rick Santorum, an also-ran in the last two Republican presidential contests, sees another chance to position himself as the steady conservative alternative to Mitt Romney – by taking advantage of a weakened Newt Gingrich.

Santorum was already off and campaigning in Missouri and Colorado as Gingrich endured a blowout Florida loss to Romney, after a brutal campaign in which his record, character and even mental stability were questioned.

On Wednesday, Santorum won the endorsement in Colorado of Tom Tancredo, a former congressman who is a tea party favorite and a hard-liner on undocumented immigration. He is pitching himself as an issues-oriented conservative who is not involved in what he called the “mud wrestling” personal attacks between Gingrich and Romney. “We as Republicans can do better than what we’ve seen in Florida,” Santorum said.

Also on Wednesday, allies of Santorum went on the air in Missouri with a 30-second spot that touts him as the “one principled” Republican able to defeat President Obama. The ad is sponsored by the Red White & Blue Fund, a super PAC supporting Santorum’s bid; the super PAC says it has made a “six figures” purchase of air time.

Missouri is seen as a good opportunity for Santorum to prove himself, since Gingrich did not qualify for the ballot there.

Santorum’s campaign itself is broadcasting an ad in Colorado and Nevada that compares Gingrich to Obama and Nancy Pelosi, the liberal Democratic former House speaker. It attacks Gingrich for backing the Wall Street bailout plan, his past advocacy of an individual mandate to purchase health insurance, and legislation that would combat climate change by limiting carbon emissions.

The RW&B takes aim at the president.

“Obama’s reckless agenda must be stopped,” the announcer says. “And there’s only one principled candidate with the courage to do it. Rick Santorum. Father. Husband. A champion for life.”