"I think he’s doing well just because he’s thinking, and people are hungry for ideas that make some sense," Clinton told NewsMax. "He's being rewarded for thinking."
He also praised the candidate's debate performance, though he declined to predict a primary win.
"I still think Romney comes across as strong and forceful and knowledgeable and I thought Perry had a better debate last night, he did much better than he's doing," he said.
The former president's praise is a surprise considering their contentious past. During Clinton's presidency, then-House Speaker Gingrich fought Democrats hard on such issues as Medicare and welfare reform. He also pushed for Clinton's impeachment.
More recently, though, Clinton and his allies have offered positive feedback on the GOP candidate.
"He is brilliant," Dick Morris, a former Clinton campaign strategist, told HuffPost's Sam Stein. "He's a very skilled adversary."
Clinton called Gingrich "creative, flexible, and brimming over with new ideas" in his book and, in September, predicted a comeback for GOP hopeful.