Biden Revives Campaign, Winning Nine States, but Sanders Takes California

The results also called into question Mr. Sanders’s decision to spend valuable time over the past week campaigning in both Minnesota and Massachusetts, two states where he had hoped to embarrass rivals on their home turf. The gambit proved badly flawed: It was Mr. Biden who pulled off upset wins in both states, with the help of a last-minute endorsement from Senator Amy Klobuchar that upended the race in Minnesota.

The unexpected breadth of Mr. Biden’s success, on a day when more than one-third of the delegates were at stake, illustrated the volatility of this race as well as the determination of many center-left Democrats to find a nominee and get on to challenging President Trump. The former vice president had little advertising and a skeletal organization and scarcely even visited many of the states he won, including liberal-leaning Minnesota and Massachusetts.

But his smashing victory in South Carolina echoed almost instantaneously, and his momentum from there proved far more powerful than the money Mr. Sanders and Mr. Bloomberg had poured into most of Tuesday’s contests.

The early returns were a comprehensive setback for Mr. Bloomberg, the billionaire former mayor of New York City, who entered the race late and spent more than half a billion dollars on an aggressive advertising campaign. But Mr. Bloomberg slumped badly after a series of damaging clashes with Ms. Warren, and many moderates and African-Americans appeared to have abandoned him for Mr. Biden. Hours into vote-counting, Mr. Bloomberg had won only one contest, in American Samoa.

Addressing supporters in West Palm Beach, Fla., on Tuesday night, Mr. Bloomberg tried to put the best face on a dismal evening. “Here’s what is clear,” he said. “No matter how many delegates we win tonight, we have done something no one else thought was possible: In just three months, we’ve gone from 1 percent in the polls to being a contender for the Democratic nomination for president.” Still, Mr. Bloomberg planned to review Tuesday’s results and decide his path forward in the race, people familiar with the campaign’s plans said.

Ms. Warren’s loss in Massachusetts left her without a single victory after a month of primaries and caucuses, and in many places on Tuesday she was running in a relatively distant third or fourth place. Most dispiriting to Ms. Warren may be that she lost her home state not to Mr. Sanders, who worked hard to defeat her in her home state, but rather Mr. Biden, suggesting that none of the recent tumult in the race had worked to her advantage.