CLEVELAND (AP) — Newt Gingrich, suddenly in danger of losing his perch as Mitt Romney’s strongest GOP challenger, is fine-tuning his presidential campaign to place more emphasis on raising money, guarding his home turf and trying to avoid nasty quarrels with the front-runner.

Rick Santorum’s stunning success in this week’s elections in Colorado, Minnesota and Missouri has fueled his claim that he, not Gingrich, is best qualified to rally conservatives who feel Romney is too moderate and unreliable.

Gingrich, the former House speaker, again faces a dilemma that has dogged him for much of the election. Should he show his feistier, meaner side at the risk of turning off voters who want pragmatic solutions more than expressions of anger? Or should he use a tamer, high-minded tone and risk losing economically anxious, resentful Republicans such as those who handed him his only victory, in South Carolina?

His aide R.C. Hammond said Gingrich favors the second option, at least for now.

“We need to go hard at demonstrating we are the one campaign of leadership,” Hammond said in an interview in Cleveland, where Gingrich spoke Wednesday without mentioning Santorum, Romney or his own poor showing in Tuesday’s voting.