BALTIMORE — Bernie Sanders looks to be headed for a rough ride through the Acela corridor.
Here in Maryland, where Hillary Clinton locked up much of the state’s political establishment last year while the state’s former, Gov. Martin O’Malley, was still in the race, she leads by more than 20 percentage points in the polls. On Monday, she was endorsed by The Baltimore Sun, the state's largest daily newspaper.

It’s a similar story in each of the four other Northeastern states voting Tuesday — Connecticut, Delaware, Pennsylvania and Rhode Island — where Sanders is also up against a wall of institutional support for Clinton. And there are other powerful forces working against him, among them, demographics and closed primaries.

Former Pennsylvania Gov. Ed Rendell, a longtime Clinton supporter, predicted that the four states using a closed primary format — where only registered Democrats can vote in the Democratic primary — will prove especially challenging for Sanders, whose best primary performances have come in states where voters don’t need to be Democrats to participate.

“Wherever it’s a primary for Democratic voters she does much better,” Rendell said of Clinton.