Obama privately told a group of Democratic donors last Friday that Sanders was nearing the point at which his campaign against Clinton would end, and that the party must soon come together to back her, the New York Times reported.

Sanders, a Vermont senator and self-proclaimed democratic socialist, while saying he did not want to comment directly on Obama’s reported remarks, pushed back on the idea that his campaign had run its course and he should throw in the towel.

“The bottom line is that when only half of the American people have participated in the political process … I think it is absurd for anybody to suggest that those people not have a right to cast a vote,” Sanders told MSNBC in an interview.

The White House on Thursday said Obama did not indicate which candidate he preferred in his remarks to the donors.

Clinton, a former secretary of state in the Obama administration, has a large lead in the race for the Democratic nomination and she won all five states that were contested on Tuesday.

Sanders said he will do better in upcoming contests in western states, after losing to Clinton in a number of southeastern states.

“To suggest we don’t fight this out to the end would be, I think, a very bad mistake. People want to become engaged in the political process by having vigorous primary and caucus process. I think we open up the possibility of having a large voter turnout in November. That is exactly what we need,” Sanders said.

“A low voter turnout, somebody like a Trump can win. High voter turnout, the Democratic candidate will win,” he said, referring to Donald Trump, the front-runner in the race to pick the Republican nominee for the November presidential election.