Mitt Romney isn't running for President of the United States in the upcoming election, but he's still paying close attention to the race, according to The Washington Post.

Romney spoke to college students at Georgetown University in Washington, D.C. Wednesday and answered questions about the current Republican primary. "I would have never predicted that the leader of my party at this stage would be Donald Trump and the leader in their party right now would be a socialist," he said. The unnamed candidate Romney mentioned is Bernie Sanders, who is running against Hillary Clinton for the Democrats.

Trump endorsed Romney in the 2012 election, which Romney lost to President Barack Obama, but Trump isn't getting an endorsement in return. "Donald Trump will not be the nominee. Ultimately our nominee will come from the mainstream conservative bracket. I don't know who that will be," Romney said, The Washington Post reported.

"I will support the Republican nominee. I don't think that's going to be Donald Trump," he added, according to The Huffington Post.

Romney has not publicly endorsed any of the candidates in the Republican primary election so far, but he has made it clear that he's not supporting Trump.

"My party has historically nominated someone who's a mainstream conservative, and someone who has a foundation of foreign policy that gives people confidence that can guide ship in a state of troubled waters," Romney said, according to ABC News.