Senator Bernie Sanders said he plans to meet with his U.S. presidential campaign rival Hillary Clinton, the presumptive Democratic nominee, on Tuesday night after the party’s final primary election is concluded.

The meeting is being held to discuss the party’s platform, which Sanders hopes to shape more in line with his support for higher taxes on the wealthy and greater help for working and poor people, he said Sunday on ABC’s “This Week With George Stephanopoulos.” The meeting was confirmed by a Clinton campaign official who wasn’t authorized to speak on the record.

“I will be meeting with Hillary Clinton, as I understand it, on Tuesday evening,” Sanders said. The Vermont senator said he wants to discuss “what kind of administration she will have” if she wins in November.

While Sanders stopped short of saying he plans to concede to Clinton, his comments sent the strongest signal to date that he is now trying to shape the party and the fall campaign against Republican Donald Trump rather than continuing to pursue the nomination by lobbying superdelegates or planning to disrupt the Democratic National Convention in July. The shift follows a meeting at the White House with President Barack Obama on Thursday.

“I am doing everything that I can and will continue to do everything that I can to make sure that Donald Trump does not become president of the United States,” Sanders said on NBC’s “Meet the Press.” “I think this man in a dozen different ways is not fit to become president.”

The District of Columbia holds the final Democratic primary on Tuesday, and Clinton is favored to win a majority of its 20 pledged delegates. The Associated Press said Clinton had obtained the necessary delegates to secure the nomination on June 7, a day before she won sizable victories in states including California, the state with the highest number of delegates, and New Jersey.