Democratic pollster Doug Schoen has penned an op-ed in the Wall Street Journal predicting that Hillary Clinton could be denied the Democratic Party nomination if Sen. Bernie Sanders (I-VT) wins the June 7 California primary.

According to Schoen, a loss for Clinton would not only demonstrate her weakness as a national candidate, but could also turn the tide of opinion in the embattled Democratic National Convention and among wavering “superdelegates” — party bigwigs with an independent vote.

Specifically, Schoen argues, Sanders could seize the opportunity to change the convention rules to force superdelegates to cast their ballot for whichever candidate won their state. (In many states, Sanders won delegates at the ballot box, only to lose to Clinton overall because of her superdelegate lead.)

In addition, he says, Vice President Joe Biden may be eager to enter the fray.

Schoen writes:

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… Mr. Biden would be cast as the white knight rescuing the party, and the nation, from a possible Trump presidency. To win over Sanders supporters, he would likely choose as his running mate someone like Sen. Elizabeth Warren who is respected by the party’s left wing.

(Read Schoen’s full article here.)

In addition, Schoen writes, Clinton faces increasing pressure from the FBI investigation into her personal e-mail server and apparent conflicts of interest involving her family foundation and her performance as Secretary of State.

Schoen is a Fox News contributor, and has worked for the Clintons in the past.

<em>Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new e-book, </em><a href=”http://www.amazon.com/gp/product/B01CN4KNB6″ target=”_blank”>Leadership Secrets of the Kings and Prophets: What the Bible’s Struggles Teach Us About Today</a><em>, is on sale through Amazon Kindle Direct. Follow him on Twitter at <a href=”https://twitter.com/joelpollak”>@joelpollak</a>.</em>