Posted: 7:09 AM Last Updated: 8 hours ago •By: Kevin Liptak, CNN His 2012 presidential bid ended in defeat during the primaries, but that may not have been the last of candidate Newt Gingrich. Asked Sunday on NBC's "Meet the Press" if he would run for the White House again, the former House speaker put on an enormous Cheshire cat grin and said: "I doubt that, but one never knows." At the end of November, Gingrich told a crowd at a book signing in Florida he had "no idea" whether he would run again in 2016. One factor: his potential Democratic rival. Gingrich said Sunday if Hillary Clinton decides to put her name in contention, Republicans face an uphill climb. "If their competitor in '16 is going to be Hillary Clinton, supported by Bill Clinton and presumably a still relatively popular President Barack Obama, trying to win that will be truly the Super Bowl," he said. "And the Republican Party today is incapable of competing at that level." "She is very formidable as a person. A very confident person," said Gingrich, who served as House speaker during President Bill Clinton's tenure in the White House and often sparred with the Democrat. "She is married to the most popular Democrat in the country. They both think it would be good for her to be president. That makes it virtually impossible to stop her for the nomination, I think," he predicted. If Republicans hope to stand up to Clinton -- or to any Democratic rival -- in 2016, they need to reflect on the reasons they lost the White House this year, Gingrich said. "We didn't blow it because of Mitt Romney," he said. "We blew it because of a party which has refused to engage the reality of American life and refused to think through what the average American needs for a better future."