Sanders could back up his surprise win in Michigan’s primary last week by defying polls with victories in Ohio, Missouri, and perhaps Illinois. He may then prevail in other states like Pennsylvania and Indiana and in the eight western states still set to award delegates.

Wins in those states could influence perceptions of the Democratic race, but they would not do much to help Sanders catch former Secretary of State Hillary Clinton.

Clinton had 1,235 Democratic convention delegates headed into Tuesday’s voting. Sanders had 580. The former first lady and New York senator is more than halfway to the 2,383 delegates needed to clinch the Democratic nomination.

That is a nearly insurmountable lead. Democrats award delegates proportionally, meaning that even in states Sanders wins, he makes only modest gains in delegates.

An analysis by the Cook Political Report, a nonpartisan electoral handicapper, found Sanders needs to win 61% of the remaining pledged delegates to catch Clinton. Sanders claimed at a CNN town hall on Sunday that the task is doable.

“If we do well in a number of states and if the general sentiment becomes that ‘Bernie Sanders is the candidate who will defeat Donald Trump,’” Sanders argued, superdelegates supporting Clinton, who are allowed to change their mind, might instead back him at the Democratic convention this summer.

Clinton’s lead among pledged delegates is indeed smaller, 766 to 551, according to an Associated Press tally. But the problem with Sanders’ scenario is that Clinton’s growing lead and entrenched support from party leaders leaves little chance that superdelegates will ditch her.

Clinton built her advantage with blowout wins in large states like Texas, where she won 147 delegates to Sanders’ 75, and in places like Georgia and South Carolina, where she crushed Sanders among African-American voters.

Sanders has won big, too. But his bigger victories came in states like New Hampshire, Maine, Kansas, and Nebraska, which have small populations and fewer convention delegates.

Sanders beat Clinton in Kansas with support from 68% of caucus goers, but gained just 15 delegates. Clinton’s win with 83% of the vote in Mississippi’s Democratic primary, by contrast, netted her 26 more delegates than Sanders.

Sanders upset win last week in Michigan won him headlines, but just seven more pledged delegates than Clinton.

The Michigan result barely budged predictions. After that primary, Clinton’s odds of winning the nomination fell just 2 points from 95% to a 93% on PredictWise, which aggregates market and polling data.

On Tuesday, Clinton is positioned to win easily in North Carolina and delegate-rich Florida, which Sanders has essentially conceded. No matter how Clinton performs in the Midwest, she will increase her delegate lead and push Sanders’ odds of him catching her toward zero.

Clinton campaign manager Robby Mook accurately noted last week that even if Sanders wins in Ohio, Illinois, and Missouri on Tuesday, Clinton would still net more delegates.

The New York Times’ Nate Cohn recently wrote that even in the unlikely event Sanders beats Clinton across the board going forward—winning in Wisconsin, Rhode Island, West Virginia, and Kentucky, in addition to Alaska, North Dakota, and the Rocky Mountain states— and even if Sanders throws California into tossup territory, the math doesn’t work for Bernie. “She [Clinton] still wins—and comfortably,” Cohn wrote.

To win the nomination, Sanders would need to not just beat, but badly beat, Clinton in both California and her home state of New York. Such an outcome is not looking likely.

Sanders has shown he can win states, earning him the opportunity to keep competing with Clinton through the convention. But Tuesday’s primary votes will ensure he can’t seriously compete to go on to the general election.