Bernie Sanders will be running for the US Presidential Election 2020. (File Photo)

President Donald Trump welcomed Bernie Sanders to the 2020 White House race on Tuesday, but said the Democratic hopeful probably "missed his time."

"I wish Bernie well," Trump told reporters in the Oval Office. "It will be interesting to see how he does.

"Personally, I think he missed his time," Trump said of Sanders, who lost the 2016 Democratic nomination to Hillary Clinton.

"But I like Bernie," Trump continued, saying that the two of them "sort of would agree on trade."

"I'm being very tough on trade," he said. "The problem is (Bernie) doesn't know what to do about it."

Trump also said he thought Bernie Sanders was "not treated with respect" when he ran against Clinton in 2016.

"We'll see how he does," Trump said. "We got a lot of people running. Only one person is going to win. I hope you know who that person is."

Bernie Sanders, 77, accused Trump of being a "racist" and a "pathological liar" as he launched his second bid for the White House on Tuesday.