Is John Fetterman the Future of the Democratic Party?

John Fetterman’s resounding victory in the Democratic Pennsylvania Senate primary was not surprising, but it was uncharacteristic.

Pennsylvania Democrats do not ordinarily veer too far from the center lane, and they are cautious about whom they send forward from their primaries to take on Republicans in general elections. They’re not gamblers, and given the state’s perennially up-for-grabs status and its unforgiving electoral math, you could argue they shouldn’t be.

But on Tuesday, Democrats made Mr. Fetterman, the state’s lieutenant governor, their nominee to compete for the seat being vacated by the retiring Republican Pat Toomey. (They did it despite Mr. Fetterman’s recent health scare; last week he suffered a stroke, but he said that he was on his way to “a full recovery.”)

Conor Lamb, 37, a Pittsburgh-area congressman, would have been a more conventional choice. His House voting record tracks to the center, and he has been compared to the state’s three-term Democratic senator, Bob Casey, a moderate and the son of a former Pennsylvania governor.

Mr. Fetterman, 52, offers something different, a new model for Pennsylvania. It is built on quirky personal and political appeal rather than the caution of a traditional Democrat in the Keystone State. With over 80 percent of the votes counted, Mr. Fetterman was more than doubling the total of Mr. Lamb, whose campaign, despite winning many more endorsements from party leaders, never gained momentum.

For Democrats, the stakes are high: The outcome may well determine the balance of the evenly divided U.S. Senate, future votes to confirm Supreme Court nominees and much else in our bitterly divided nation.