The problem for Team Sanders isn’t just the fact that Clinton won all five of yesterday’s contests. That’s certainly discouraging – the campaign believed it had a real chance of success in two or three of these primaries – but the far greater problem is the margins and the increasingly brutal delegate math.

Because Democrats allocate delegates proportionally, Clinton’s double-digit wins in Ohio and North Carolina, coupled with her landslide victory in Florida (the day’s biggest delegate prize), means she took a major step towards the nomination, effectively positioning herself as the presumptive nominee.

The Sanders campaign has long realized that catching up to Clinton among pledged delegates was going to be very difficult, but the senator and his team believed they could nevertheless shift the momentum in their direction. If Sanders started racking up wins – even close ones – in big states, exposing Clinton’s weaknesses in key regions and with important Democratic constituencies, he believed could plausibly tell the party’s superdelegates that he’s the stronger national candidate, Clinton’s lead among pledged delegates notwithstanding. The senator would ride a wave of momentum into the early summer.

That no longer appears to be an option. The Democratic frontrunner has more votes, more states, more delegates, and more superdelegates. Sanders could, in theory, win each of the remaining contests by 16 points, but anything short of that means he will not win the nomination.