Washington (CNN) House Speaker Nancy Pelosi warned fellow Democrats in an exclusive CNN interview that the party "must be unified" to defeat President Donald Trump in the 2020 presidential race, while noting that any of the candidates running to face him "would be a better president."

"I can't even envision a situation where he would be reelected. But we are not, we don't take anything for granted. As I say, we have to have our own vision for the future. But everybody knows that we must be unified in making sure that he does not have a second term," Pelosi told CNN's Christiane Amanpour at the Munich Security conference over the weekend.

Pelosi's comments come as a crowded field of Democratic presidential candidates continue to battle it out in the primary race to see who will go on to face Trump in the general election with the White House at stake. The field of Democratic candidates that started out with more than 20 hopefuls has winnowed down to eight following the Iowa caucuses and New Hampshire primary.

The House speaker argued that Democrats "have a better vision for America and we must defeat Donald Trump."

"We know one thing: we have a better vision for America, and we must defeat Donald Trump who does not share a vision that is about unity and unifying the country," she said.

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