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WASHINGTON — Bernie Sanders acknowledged Wednesday that he will likely not be the Democratic nominee for president, as aides privately conceded that his future in the race remains in flux.

When asked in an interview with C-SPAN’s Steve Scully if he would be speaking at the Democratic National Convention in Philadelphia this July, Sanders paused before answering.

"Well, you know it’s hard to say, it doesn’t appear that I’m gonna be the nominee, so I’m not gonna be determining the scope of the convention,” admitted the Vermont senator, two weeks after former Secretary of State Hillary Clinton was projected to be the Democratic Party’s presumptive nominee.

It's the closest Sanders has come to conceding the prolonged Democratic primary race to his opponent.

Sanders is slated to give a speech Thursday in New York to address "where we go from here," which aides said will not include a concession but will address the kinds of policies Sanders will push the party to enact.

"I expect he will focus on policy -- from income and wealth inequality to climate change -- and how he hopes the Democratic Party platform will be the most progressive ever," said spokesman Michael Briggs.

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A question that continues to linger, however, is when and if the insurgent candidate will endorse Clinton in the weeks ahead of the convention.

Aides tell NBC News that officials with both the Sanders and Clinton campaigns are in conversations about ways to incorporate some of Sanders’ main issues -- like college affordability, expanding Medicare and minimum wage --into the party platform. Also on the table is a possible endorsement of Clinton before the Democrats convene in Philadelphia, but the timeline for voicing such support remains open.

“Where we are right now with Secretary Clinton, we’re negotiating, and negotiation goes two ways,” Sanders said on C-SPAN when asked if he would endorse his Democratic rival.

Sanders said that while there was no agreement in the works to exchange a coveted speaking slot at the Democratic convention for a formal endorsement, he does expect to speak. Aides confirmed that both camps have discussed a speaking slot.

Although the Democratic primary season wrapped up on June 14, Sanders still has the benefit of a Secret Service detail. The Sanders camp says that that protection could extend to the Democratic convention in July. (Ultimately, the decision rests with Homeland Security Secretary Jeh Johnson, but it could be hastened by Sander’s determining an exit from the race or an endorsement of Clinton.)

On Wednesday, Sanders did praise Clinton as well, contrasting her to presumptive GOP nominee Donald Trump.

The presidential hopeful emphasized that Clinton’s “command of public policy” is in a “different world” from Trump's and argued that Sanders supporters would not flock to Trump.

“I suspect he ain’t gonna get too many of those,” he said.

In the wide ranging interview, Sanders also said if he were to return to his Senate job in the fall, he would seek the chairmanship of the Health, Education, Labor and Pension (HELP) committee, if the Democrats were to take back the Senate.

At the end of the primary season, Senator Sanders had earned 1,880 delegates (super and pledged) to the Democratic National Convention, to former Secretary Clinton’s 2,809, according to NBC News estimates.