One of the more effective arguments that Sen. Bernie Sanders (I-Vt.) made during his bid for the Democratic nomination in 2016 was that he, unlike Hillary Clinton, could win over working-class Midwesterners that the party would need in November. It seems more effective after the fact, certainly, given how the election turned out, but that, coupled with Sanders’s ability to hang in the fight by winning contests (often caucuses), even after Clinton had things wrapped up, gave him a useful way to defend hanging around.

This year, particularly after Tuesday’s results, his case is far shakier.

Consider, for example, the map of contests after the Nevada caucuses.

That blue represents counties won by former vice president Joe Biden — the vast majority of them, particularly east of the western edge of the Gulf Coast. Not only has Biden won state after state since his stunning victory in South Carolina, but he has often won every county in each state. Even big states such as Florida and Michigan went for Biden across the board, removing any ability of Sanders to claim that he could better appeal to rural or suburban voters.

In the 12 states running from Michigan to Florida and Oklahoma to Virginia, Sanders won 13 counties — an average of one per state. Biden won 1,027.

Counties aren’t votes, as we were also reminded in 2016. But, again, it serves as a reminder that Biden’s strength has proved not only to be deep but also broad, undercutting Sanders’s regular claims of being uniquely positioned to be able to expand the Democratic electorate.

More worrisome for Sanders is the delegate math. We don’t have final delegate allocations from the states that voted this week, but the delegate-tracking site the Green Papers has estimates based on the vote in congressional districts. Those numbers suggest that Biden’s delegate lead over Sanders nearly doubled from last week to this week.

Biden needs 1,991 delegates to clinch the nomination; the site estimates that he’s probably near 1,200 delegates even without all of the delegates from completed contests being doled out.

The problem for Sanders is that time is running out. The primary season still seems fairly young, but nearly 60 percent of the delegates who will be awarded have already been awarded, or the distribution will be based on the results of contests that have already happened. That’s because we’ve already passed three of the dates with the five-highest delegate totals. There just aren’t that many delegates left.

The map above ignored Sanders’s relative strength west of Texas, in states such as California and Utah. In California alone, he gained 49 more delegates than Biden, a big chunk that could help him eat into Biden’s lead. The problem, though, is that there aren’t many big states still outstanding, much less ones where Sanders can have the sort of margin of victory that will yield him a big delegate total. Remember, the Democratic primaries award delegates proportionally, meaning that Sanders’s winning narrowly over Biden in a big state is less useful for closing the gap than winning a smaller state massively. Sanders needs big wins in big states, and there aren’t many big states left.

Florida, which voted Tuesday, was a big state that Biden won big. The former vice president will probably net nearly 100 delegates more than Sanders there — about as many as Sanders has netted in states where he’s gotten more delegates than Biden. Sanders’s wins in Iowa, New Hampshire, Nevada, California, Colorado, Utah, Vermont, North Dakota and the Northern Marianas earned him 105 more delegates than Biden. Biden earned 95 more delegates than Sanders in Florida alone, with 14 delegates still to be allocated.

That proportionality is why Sanders is in such trouble. There are 1,755 delegates still to be allocated according to the Green Papers, meaning that Sanders needs to win 63 percent of what’s still out there to clinch the nomination. In other words, he needs to consistently beat Biden by about 25 points.

Even just to catch Biden — a necessity according to Sanders himself if he wants to contest the nomination — Sanders needs to win 58 percent of the remaining delegates (1,015 of the remaining 1,755). Sanders needs to beat Biden by 16 points across the board from here on out.

He won’t.