Since Hillary Clinton swept the Ides of March primaries on March 15, she has won only the state of Arizona on March 22. Bernie Sanders has had some rather impressive wins in state caucuses since then, and a win in the Wisconsin primary on Tuesday.
Nevertheless, because the Democratic Party uses a proportional award of delegates by the percentage of the vote, Clinton keeps closing in on her win number, while Sanders still has a long way to go to catch up. Jonathan Martin and Nate Cohn explain: “Mr. Sanders’ overall deficit — he trails Mrs. Clinton by about 230 delegates — is becoming so large that winning only modest victories puts the Democratic nomination farther out of his reach.”
After Wisconsin, NBC News’s First Read does the math and concludes that Sanders gained no ground:
[Sanders] outspent Clinton over the Wisconsin airwaves by nearly a 3-to-1 margin, beat her by 14 percentage points, 57%-43%, but only picked up a net gain of just 10 pledged delegates. And despite that gain, the percentage of overall remaining delegates that Clinton needs to clinch the nomination actually got smaller (from 34% to 33%), because there are fewer delegates left to win…. Clinton must win 33% of remaining delegates to hit the 2,383 magic number (was 34%). Sanders must win 67% of remaining delegates to hit the 2,383 magic number (was 66%).
Wisconsin was an open primary. Sanders does far better in contests open to independents than in closed ones. But the big upcoming contests in New York (April 19), and Pennsylvania, Maryland, and Connecticut (April 26) are closed primaries, which are confined to those registered as Democrats.
Clinton has won big in racially diverse urban electorates. Clinton wins in these upcoming contests would foreclose any path to the nomination for Sanders. Even a narrow loss, beating the 33% need to win number, would inexorably move Clinton closer to her win number. It is always about the delegate math.
Democratic primaries in May that are closed primaries include Kentucky and Oregon. New Mexico is also a closed primary in June.