On Tuesday, Senator Bernie Sanders ended his campaign for president and endorsed former Secretary of State Hillary Clinton. Nothing says “political revolution” like endorsing someone for high office that stands in opposition to most (if not all) of your revolutionary political program.

Of course, Senator Sanders always said he would endorse the party’s nominee. So while Sanders can be rightly accused of undermining the policies he claims to support by endorsing a Wall Street Democrat with a neoconservative foreign policy, he is following his partisan promise. Judge the virtues of that commitment as you will.

But one aspect of the endorsement is very puzzling: the timing. Senator Sander repeatedly stated, as recently as last month, that he would take his campaign “all the way to convention”—that, if nothing else, his continued campaigning would force a more progressive party platform.

So why did he concede yesterday? Clinton supporters desperately noted Clinton sealed the nomination through the party’s rigged-together system in June. That’s when Sanders once again said he was going all the way to the convention. The move was extremely curious. It was a sudden and seemingly premature abandonment of his remaining leverage to push the platform to the left.

A cynical man might speculate that, despite public claims about not caring about Clinton’s “damn emails,” Sanders believed there was a good chance Clinton could face criminal indictment related to said emails, in which case Clinton would have to drop out of the race and Sanders would be well-positioned to claim to be the rightful nominee of the Democratic Party.

It wouldn’t be a bad calculation. FBI Director Comey’s public statement proved Hillary Clinton lied about her email activities, but, as Comey later explained to Congress, he decided a reasonable prosecutor would not bring a case. Judge the validity of that claim as you will.

In any case, Sanders has now conceded the race before the convention and promised not to start floor fights based on the party platform. Furthermore, he gave a fawning endorsement of Clinton that alienated many of his supporters.

So, was Bernie Sanders just waiting on the FBI? Did he believe he legitimately lost the race in June and was holding out in case Clinton would be indicted? If so, Sanders is a bit more opportunistic than his persona would allow.