Meanwhile, Sanders’s senior strategist, Tad Devine, told the AP that the campaign would need to “sit back and assess where we are” after the results of upcoming primary contests. Devine reportedly maintained that it would still be possible for Sanders to secure the nomination. But his wait-and-see tone seemed to signal uncertainty. It appeared to be the first hint of publicly expressed doubt on the part of the campaign over the fate of the race.

The longer Sanders stays in the race, the more time he has to preach his message of political revolution. If he fights all the way to the convention, Sanders may be able to extract concessions from Clinton and the Democratic Party, assuming Clinton ends up in position to receive the nomination. If Sanders drops out of the race before the convention, the delegates he has won would be free to move on to Clinton, and Sanders would risk losing the leverage he has worked so hard to win.

Still, Sanders’s ability to use that leverage could hinge on whether he can avoid alienating Clinton, the Democratic establishment, and liberal voters. Sanders has expressed a belief that he can win over superdelegates for some time. But his campaign seems to be putting a sharper point on that argument, effectively suggesting party elites can deliver the nomination to the Vermont senator.

MSNBC’s Steve Kornacki sketched out the following scenario for Weaver on Tuesday:

If June 7 comes and goes, and Hillary Clinton has won the pledged delegate count in the primaries, and she’s won the popular vote, there are going to be calls … for you, the Sanders campaign, to make a decision to unite around her. You’re saying instead of that, you will spend those months, those weeks in the summer, trying to flip superdelegates to Bernie Sanders before the convention.

“At this point, yes, absolutely,” Weaver replied. That argument clashes with the campaign’s argument that it represents the voice of the people, and could hurt Sanders’s standing with voters who love him precisely because he rails against a rigged system where political power brokers call the shots. It’s also a long-shot strategy considering that superdelegates typically side with whichever candidate has the most popular support at the end of primary-voting season.

Team Sanders has also shown an increased willingness to challenge the Democratic Party and the Clinton campaign. The campaign raised the possibility on Monday that Clinton and the party may have violated campaign-finance laws as a result of a joint-fundraising effort. The claim puts Sanders squarely at odds with the Democratic Party. It also feeds a negative public perception, often stoked by Republicans, that Clinton is willing to break the law to consolidate power, even though at least some campaign finance and election experts suggest the fundraising was likely above board. The claim will certainly help Sanders gin up support from his followers. It could also help his campaign spotlight fundraising practices the senator believes should be illegal, even if they’re not illegal now.