Nicole Gaudiano

USA TODAY

WASHINGTON — Sen. Bernie Sanders says he still sees a path to the Democratic presidential nomination, even after Hillary Clinton won at least four more nominating contests on Tuesday.

Sanders is pinning his hopes on contests coming up in the West.

“With more than half the delegates yet to be chosen and a calendar that favors us in the weeks and months to come, we remain confident that our campaign is on a path to win the nomination,” he said in a statement.

Sanders believes his campaign, fueled by passionate supporters donating online, can continue until final contests in June. He will hold events this week in Arizona, Idaho and Utah, where voters will go to the polls on Tuesday and where Sanders expects to do well. His campaign also sees opportunities in Alaska, Hawaii and Washington state, which hold caucuses the following Saturday, on March 26.

But the Vermont independent’s path forward looks less likely, mathematically, after Clinton's victories Tuesday in Florida, Illinois, North Carolina, and Ohio marked an apparent turning point in the campaign. On Wednesday, the primary in Missouri remained too close to call, with Clinton up by just 1,531 votes out of 619,673 cast.

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Clinton now has 1,139 pledged delegates to Sanders’ 825. When counting superdelegates, who are free to support the candidate of their choice, the former secretary of State is only 777 delegates short of the 2,383 needed to clinch the nomination. Sanders is 1,532 delegates short.

The Sanders campaign believes superdelegates will follow the will of voters if he wins future contests. In terms of pledged delegates, this is the "high water mark" for Clinton's campaign and Sanders will soon begin to erode that advantage, Sanders' campaign manager, Jeff Weaver, said Wednesday.

"There are going to be some important showdowns over the next few weeks," Weaver said in a conference call with reporters.

However, Sanders would need to win 58% of remaining pledged delegates — or 66% of all remaining delegates, including superdelegates — to tie Clinton, said David Wasserman, who analyzes delegate counts for the Cook Political Report.

"It ain't happening," Wasserman wrote in an email. "The Democratic race is pretty much over. The pressure to leave the race will intensify, but as long as he's still 'mathematically' in contention, don't expect him to respond to it."

Clinton hasn't called on Sanders to leave the race, but her victory speech Tuesday night focused on defeating Republican frontrunner Donald Trump in the general election.

“We are moving closer to securing the Democratic Party nomination and winning this election in November,” she said.

After Sanders scored an upset victory in Michigan's primary on March 8, expectations were high that he would perform well in the three Midwestern industrial states — Illinois, Missouri and Ohio — that held contests on Tuesday. In advance of those primaries, Sanders hammered Clinton for supporting trade deals that he said had moved jobs overseas.

But exit polls in Ohio showed Clinton won among voters who believe trade with other countries would cost U.S. jobs, as well as voters who believe it would create jobs. She also won among those most concerned about the economy and jobs.

In Florida, she won by a large margin among Latinos, who are key to winning the nomination.

When she ran for the Democratic presidential nomination in 2008, Clinton didn’t suspend her campaign until June, after Barack Obama had secured enough delegates to become the nominee. But Clinton's campaign manager Robby Mook noted in an open memo Wednesday that Clinton’s lead over Sanders in pledged delegates is nearly twice as large as any lead Obama enjoyed in 2008.

Mook conceded that Sanders likely will win the next five caucuses and do well in Arizona, where he said Sanders has invested more than $1.5 million in ads.

“But our pledged delegate lead is so significant that even a string of victories by Sen. Sanders over the next few weeks would have little impact on Sec. Clinton’s position in the race,” he wrote.