WASHINGTON • Newt Gingrich said Sunday that he and other Republican presidential candidates must win their home turf contests or face serious questions about continuing in the race.

The first test will come Feb. 28 in the GOP primary in Michigan, where rival Mitt Romney was born and his father was governor.

If Romney loses in Michigan, "I don't know what he says the next morning to his donors to stay in the race," Gingrich told "Fox News Sunday."

But Gingrich also acknowledged that he must win the March 6 vote in Georgia, a state that launched his political career more than 30 years ago. The same, he said, goes for Rick Santorum during the April primary in Pennsylvania, where Santorum was a senator.

"If any of the three loses our home state ... you have, I think, very, very badly weakened candidacies," Gingrich said. "I was home campaigning for the last two days precisely to say to all of my friends back home, Georgia really matters. You cannot take this for granted."

But Gingrich stopped short of saying he would drop out if he lost Georgia "given the chaos of this race."

The Republican rivals face a series of nine primaries and four caucuses from now through Super Tuesday on March 6.