Trailing in the Democratic presidential race, Bernie Sanders has one last gambit. He wants to persuade the party’s superdelegates—officeholders, luminaries, and party officials who can vote at the convention—that he’s the Democrats’ best hope to win the general election. Never mind that Hillary Clinton has won more votes and elected delegates. “There are a lot of delegates out there who are looking at the general matchup,” Sanders argued Sunday on CNN. “And what they’re seeing in polls is that Bernie Sanders is running a lot stronger against Donald Trump than is Hillary Clinton.”

It’s true that Sanders does better than Clinton in hypothetical matchups against the Republicans. Currently, Sanders outperforms Clinton by more than seven percentage points against Trump, and by nearly nine points against Ted Cruz. But that’s not because Sanders is the stronger nominee. It’s because Republicans haven’t yet trashed him the way they’ve trashed Clinton. Once they do, his advantage over her would disappear.

In recent days, several writers—Sahil Kapur in Bloomberg Politics, David Corn in Mother Jones, Greg Sargent in the Washington Post, Ed Kilgore in New York, and others—have sketched this argument. But is it true? Polls suggest it is. A concerted attack on Sanders’ weaknesses would hurt him badly in a general election. Here’s how it would look.