Bernie Sanders looked as if he would limp into the California primary and watch his upset bid over Hillary Clinton fizzle, but a surge in the polls and rumblings that superdelegates committed to Clinton may be showing hesitation has given his campaign new energy.

In recent weeks, Clinton appeared to hold a wide lead over Sanders in the Golden State. Polls showed her lead to be somewhere in the range of 15 to 18 points over Bernie Sanders, pointing to a win that would seal the nomination, thanks to Clinton’s big lead in the party-picked superdelegates, many of whom committed to her before a single vote was cast this year.

The past week saw an abrupt change, however. The latest set of polls from California showed the two candidates in a dead heat, and a new USC Dornsife/Los Angeles Times poll this week found that Sanders had actually taken a slim lead.

The Los Angeles Times noted that support for Bernie Sanders in California appears to be deep, as he has cut into demographics once held tightly by Clinton, including Latino and Asian voters.

Wash Post: Sanders in striking range of winning California thanks to huge support from Latinos and Asian Americans https://t.co/11waVvFJj9 — Ali Abunimah (@AliAbunimah) June 3, 2016

A narrow win in California would not be enough for Bernie Sanders to erase Hillary Clinton’s wide lead in delegates, but there are signs that it could turn the tide in the race. Hillary Clinton has faced growing problems from her email scandal, with an ongoing FBI investigation into her unauthorized use of a private email server during her time as Secretary of State and a recent State Department inspector general’s report that slammed her for violating policy regarding the server.

Sanders Explains Why He Keeps Going And May Just Win California on Tuesday https://t.co/whFQCS35VH #NotMeUs pic.twitter.com/JW67Fp3jSD — The Progressive Mind (@Libertea2012) June 4, 2016

There is a growing sentiment that a win in California for Sanders — especially one by a healthy margin — could be a race-changing moment. Douglas E. Schoen of the Wall Street Journal wrote that a win by Sanders would underscore Clinton’s weaknesses and could give superdelegates the justification they need to change to Sanders. It could also give way to a giant shift at this summer’s Democratic National Convention, Schoen wrote.

“A Sanders win in California would powerfully underscore Mrs. Clinton’s weakness as a candidate in the general election. Democratic superdelegates—chosen by the party establishment and overwhelmingly backing Mrs. Clinton, 543-44—would seriously question whether they should continue to stand behind her candidacy.” “There is every reason to believe that at the convention Mr. Sanders will offer a rules change requiring superdelegates to vote for the candidate who won their state’s primary or caucus. A vote on that proposed change would almost certainly occur—and it would function as a referendum on the Clinton candidacy. If Mr. Sanders wins California, Montana and North Dakota on Tuesday and stays competitive in New Jersey, he could well be within 200 pledged delegates of Mrs. Clinton, making a vote in favor of the rules change on superdelegates more likely.”

This is no longer a hypothetical argument, either. David Shuster reported this week that many superdelegates are already preparing to leave Hillary Clinton and move to Sanders if he wins in California. So far, none have changed to the Sanders camp, but if there is growing concern among superdelegates, it could just take a handful changing sides to give others on the fence the justification they need to leave the troubled frontrunner.

Citing email investigations + comparative polls v Trump, several @HillaryClinton superdels suggest they'll switch if @BernieSanders wins CA — David Shuster (@DavidShuster) June 2, 2016

It would still take a big win for Bernie Sanders to set the plan into motion. He would likely need to defeat Hillary Clinton not only in California but either pull off an upset in one of the other large contests — New Jersey or New Mexico — or at least hold Clinton to a virtual tie. If he can do that and get some help in the form of the FBI moving forward on its email investigation, then Bernie Sanders could still be in contention for the Democratic nomination.

[Photo by Natalie Behring/Getty Images]