Former Vice President Joe Biden and Sen. Bernie Sanders solidified their frontrunner status in the Democratic presidential race Tuesday. 

In contests across the United States, there were 1,357 delegates up for grabs. Candidates must win at least a 15 percent of the vote statewide or in a congressional district to accrue delegates. 

The Associated Press projected Biden won the states of Alabama, Arkansas, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas and Virginia, while Sanders won Colorado, Utah, Vermont and California. The former mayor of New York, Mike Bloomberg, won the caucuses in American Samoa.

“Sanders had a difficult road ahead even before the massive swing to Biden and now it looks like a Sanders nomination would be nearly impossible,” said Mack Shelley, Iowa State professor and chair of the political science department. 

However, Biden could run into difficulty trying to gain support from “Sanders’ youth-powered support,” Shelley said. 

Bloomberg announced the end of his presidential campaign and endorsed Biden early Wednesday.

Bloomberg spent more than $500 million on his campaign that he began in November 2019.

“After yesterday’s results, the delegate math has become virtually impossible — and a viable path to the nomination no longer exists,” Bloomberg said in a statement to NBC news. 

Bloomberg said he would stay in the fight until November, backing Biden.

“I’ve had the chance to work with Joe on those issues over the years, and Joe has fought for working people his whole life,” Bloomberg said. “Today I am glad to endorse him — and I will work to make him the next president of the United States.”

With Bloomberg’s endorsement, Biden’s campaign will receive money from Bloomberg, “the bank of Biden,” Shelley said. 

Sen. Elizabeth Warren is reassessing her campaign after the loss of her home state, Massachusetts. 

“Warren is running very low on options,” Shelley said, “Finishing third in her home state of Massachusetts is not just embarrassing, but drives home the reality that she has no path to the nomination.”

In an email to the New York Times, Warren’s campaign manager, Roger Lau said, “We fell well short of viability goals and projections, and we are disappointed in the results.”

Whether Warren will release her delegates or endorse another candidate remains an open question, Shelley said.