said Thursday he would work to defeat presumptive Republican nomineein November, following a meeting with President Obama at the White House.

Sanders said he would speak with his rival,, about how to fight against Trump, but declined to endorse her or drop out of the presidential race.

“Needless to say, I am going to do everything in my power, and I will work as hard as I can to make sure Donald Trump does not become president of the United States,” the Vermont senator said.

Sanders said he phoned Clinton, who clinched the nomination this week, after Tuesday's primaries to congratulate her on her "strong campaign" and said they would speak soon about "how we can work together to defeat Donald Trump and to create a government that represents all of us and not just the 1 percent.”

He said Trump “would be a disaster as president of the United States” and expressed confidence that voters would not support someone who insults women and minority groups.

The senator’s pledge to cooperate with his opponent is the clearest indication yet he’s preparing to wind down his campaign.

Sanders has faced a growing number of calls from allies in Congress and groups such as MoveOn to exit the race to allow Clinton to unite the party ahead of November’s general election.

Sanders reiterated that he would compete in next Tuesday’s primary in Washington, D.C., but also pointed out it’s the final contest in the primary process.

The liberal senator is planning to hold a campaign rally later Thursday to energize voters in the city.

Sanders spoke from prepared remarks, typed on sheets of paper, and took no questions from the throng of reporters gathered on the West Wing driveway.

The senator emerged from the White House more than an hour after his meeting with Obama began, but he said little about their conversation. It was a change from his last meeting with Obama, in January, when he answered questions and detailed his discussion with the president.

Standing beside his wife, Jane Sanders, he thanked Obama and Vice President Biden for keeping “a degree of impartiality” throughout the 13-month Democratic primary.

“They said from the beginning that they would not put their thumb on the scale,” he said. “In fact, they kept their word, and I appreciate that very greatly.”

Sanders’s comments are likely to please Obama and Democratic leaders. But they could upset his legion of backers, who want him to continue his fight for the nomination.

Sanders made mention of taking his issues to the Democratic National Convention in July. But he did not speak about contesting the nomination on the convention floor or flipping superdelegates, as he has in recent days.

Obama rolled out the red carpet for Sanders, whose campaign lasted longer than anyone ever anticipated.

After Sanders arrived, he walked down the Rose Garden colonnade with Obama into the Oval Office, a gesture typically reserved for world leaders.

The two men, who have clashed in the past, smiled and laughed during their stroll. Sanders twice patted Obama on back.

The senator’s return to Washington generated enormous interest.

White House staffers lined the steps of the Eisenhower Executive Office Building to try to catch a glimpse of the Sanders, who has drawn millions of supporters to rallies on the campaign trail.

And he seemed to relish his return to the nation’s capital. Eschewing the White House mess, he stopped at a Peet’s Coffee to grab a quick breakfast before his meeting with the president.

Sanders is meeting later Thursday with Senate Minority Leader Harry Reid Harry Mason ReidGraham signals support for confirming a Supreme Court nominee this year Trump signals he will move to replace Ginsburg 'without delay' Senate Republicans signal openness to working with Biden MORE (D-Nev.). He is also scheduled to huddle with Biden and Sen. Charles Schumer Chuck SchumerVideo of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral Graham signals support for confirming a Supreme Court nominee this year Pelosi orders Capitol flags at half-staff to honor Ginsburg MORE (D-N.Y.)