Heidi M. Przybyla

USA TODAY

Bernie Sanders prevailed in Wisconsin’s Democratic primary Tuesday, continuing his winning streak over Hillary Clinton.

In a victory speech from Wyoming — which holds a caucus on Saturday — Sanders claimed momentum and argued he is a stronger general election candidate than Clinton.

“We are defeating Donald Trump by very significant numbers,” Sanders said of the Republican front-runner, before taking aim at the billionaire class, the fossil fuel industry and super PACs that are funding other campaigns. "Yes, we can change the status quo when we think big and when we have a vision," said Sanders. "I am not naive, I know the power of Wall Street and their endless supplies of money."

Clinton tweeted congratulations to Sanders, adding "to all the voters and volunteers who poured your hearts into this campaign: Forward!"

With his win in the Badger State, Sanders has pocketed six of the past seven contests, even though he's barely denting Clinton's sizable delegate lead.

Earlier Tuesday, his campaign manager, Jeff Weaver, says his streak is proof the candidate can still close the gap in pledged delegates, which stood at 263 entering Tuesday's primary, according to the Associated Press.

Whoa, Wisconsin: Speed bump for Trump, Clinton

Weaver told CNN that he believes the battle will continue until the party’s nominating convention in July. Democratic strategists are more skeptical.

“He can assert it, but it seems extremely unlikely” that Sanders can catch Clinton, said Steve Elmendorf, deputy campaign manager for John Kerry's 2004 Democratic presidential campaign. “The numbers don’t add up,” said Elmendorf, who supports Clinton but is not working for her.

Democrats do not award delegates on a winner-take-all basis, making it difficult for underdogs to overcome large deficits. Sanders would have to win big primary states, such as New York and California, by large margins in order to catch Clinton.

While the Vermont senator has won a number of smaller caucus states by large margins, including Washington and Alaska, Sanders has won only two primaries with more than 60% support: his home state of Vermont and neighboring New Hampshire. Polls show Clinton up by 10 points in the next major contest on the primary calendar: New York, which she represented for eight years in the U.S. Senate.

“Many would consider that an embarrassment for Hillary Clinton" if she didn't win by a margin larger than that, said David Wasserman, an elections analyst at the nonpartisan Cook Political Report. “And yet it would seal the deal even more for Hillary Clinton” because she would expand her delegate lead, he said.

Still, Wisconsin exit polls underscore Clinton’s longer term challenges in exciting Democrats to back her. Just six in ten say she’s honest and trustworthy. Sanders also ran even with Clinton among female voters, who’ve carried her in other races. He won both higher and lower-income voters, including union households, and broke even with her with moderates.

Wisconsin airwaves feelin’ the Bern

As the campaign heads toward New York, which holds its primary on April 19, the forecast remains the same: The race is likely to wrap up in June, when California voters head to the polls.

Sanders is burrowing in for a floor fight. He’s suggesting that delegates from states he won should flip to his column, and his campaign is approaching delegates one-on-one to back the candidate.

As for the Clinton campaign, both the candidate and her staff are showing signs of irritation. On Monday night, Clinton campaign manager Robby Mook released a memo titled “The Facts on Where the Race Stands.”

In it, he says Clinton has “built a nearly insurmountable lead among both delegates and actual voters.” Since Clinton has 2.5 million more votes than Sanders, superdelegates who back him would be going against the will of the voters, said Mook.

“We know that the misleading spin will continue, but we wanted you to know the facts,” Mook wrote.

In a Tuesday town hall in Brooklyn, Clinton took some shots at Sanders, particularly on his plan to provide free college tuition and his vote in 2005 to provide legal immunity for gun manufacturers. The Clinton campaign is betting that Sanders is especially vulnerable on the gun issue in New York, which tightened its laws in response to the 2012 Sandy Hook Elementary School shooting in Newtown, Conn.

“We’re not going to quit, we’re going to keep going at this every chance we get,” said Clinton.

Hillary Clinton raised $29.5 million in March

Clinton is having to fight harder and longer than she’d planned to seal the nomination. Even as the race moves to New York, a state that she hoped to carry by a large margin, the race will be tight, said Dan Gerstein, director of Gotham Ghostwriters and an independent political analyst in New York City.

“It’s going to be a continuation of the more global dynamic,” said Gerstein. “She’s going to win. It’s going to be closer than it should be.”

Yet a closer-than-expected race does not translate into an upset, and Democrats are citing the 2008 Democratic race as proof that Clinton is not in any real danger. It wasn’t until the final day of primaries, on June 3, that then-senator Barack Obama gained enough pledged and superdelegates to become the nominee.

It was only then that Clinton conceded.