Eliza Collins

USA TODAY

Hillary Clinton's seemingly inevitable march to the Democratic presidential nomination may still be in doubt, according to a former pollster and political adviser to Bill Clinton.

Douglas E. Schoen, in an editorial in The Wall Street Journal, said that a Bernie Sanders win in California could blunt Clinton’s path to the nomination — even if she captures the required number of delegates to hit the majority (she’s currently less than 80 away when super delegates are included, according to the Associated Press).

“The inevitability behind Mrs. Clinton’s nomination will be in large measure eviscerated if she loses the June 7 California primary to Bernie Sanders,” Schoen writes. “That could well happen.”

California, as do all states under Democratic primary rules, will allocate its 475 pledged delegates proportionally based on the primary results.

The former secretary of State is ahead of Sanders in the state by about 9 points, according to the RealClearPolitics rolling average, but recent surveys vary widely. A Public Policy Institute of California poll has Clinton ahead by just 2 points, while a KABC/SurveyUSA survey that ended the same day had her ahead by 18.

In his editorial, Schoen highlights the argument that Sanders has been making for a while now: If he continues to gain momentum, the superdelegates — party leaders and elected officials free to support anyone — will have to change their votes to go with the will of voters.

“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,” he writes.

“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.”

Schoen then ticks off a series of what he sees as Clinton’s weaknesses, including the closing gap in the polls in a general election matchup with Trump, her legal troubles related to her private email server and a lack of trust from voters.

In what could only be described as highly unlikely scenarios, Schoen also suggests it's still possible that Secretary of State John Kerry, or more plausibly, he says, Vice President Biden could still claim the nomination.

“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,” he said.