Hillary Clinton might not become the Democratic nominee, according to former Bill Clinton adviser Douglas E. Schoen.

In what could be described as one of the first acknowledgments of a tight Democratic race emerging from the pool of Bill Clinton’s former political aides, Schoen wrote in an op-ed in the Wall Street Journal that Vermont senator Bernie Sanders could still pose a big problem for Hillary Clinton if he manages to win the California primary on June 7.

Pollster and former Bill Clinton advisor @DouglasESchoen explains why Hillary Clinton may not be the nominee: https://t.co/hBtqrLXfId — WSJ Editorial Page (@WSJopinion) June 2, 2016

Arguing that latest polls have seen Sanders inch closer to Clinton in California, coupled with the fact that the senator tends to outperform the former Secretary of State in primaries, Schoen pointed out that a Sanders’ win in California could force a change of rules in the Democratic convention.

“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 a scenario which has often been underlined by Bernie Sanders as one of the viable ways in which he could still win the Democratic nomination, but this is perhaps the first time that someone belonging to Bill Clinton’s former camp has admitted that Hillary Clinton cannot — and should not — take the nomination for granted.

Moreover, Schoen wrote that Clinton’s continually worsening performance against Donald Trump in the national polls could be another reason that could go a long way in convincing superdelegates to side with a candidate whom polls have shown comfortably beating the Republican presumptive nominee nationally.

A string of recent polls, including those conducted by Real Clear Politics and ABC/Washington Post, have seen Hillary Clinton’s lead over Trump evaporating, while those same polls have shown Bernie Sanders’ lead over Trump increasing by up to 10 points.

New polls show Hillary Clinton and Donald Trump neck-and-neck https://t.co/sSQh2Bw9Vu via @GregJKrieg pic.twitter.com/tjPBLv0Z9M — CNN Politics (@CNNPolitics) May 22, 2016

Schoen also drew attention to Clinton’s expanding legal troubles, with a recent State Department report confirming that she had deliberately broken federal protocols while serving as the Secretary of State. Reports suggest that she will be interviewed by the FBI before the convention in Philadelphia, and experts believe that even an indictment could be in the cards for the Democratic front-runner. While such a scenario remains unlikely, Clinton’s efforts at creating an image of herself as a responsible leader have certainly taken a hit with voters not trusting her by a ratio of four to one.

“Finally, with Mrs. Clinton’s negative rating nearly as high as Donald Trump’s, and with voters not trusting her by a ratio of 4 to 1, Democrats face an unnerving possibility. Only a month or two ago, they were relishing the prospect of a chaotic Republican convention, with a floor fight and anti-establishment rebellion in the air. Now the messy, disastrous convention could be their own.”

Schoen went so far as to suggest that President Barack Obama may have to intervene if such a scenario was to indeed unfold over the next few weeks, arguing that even a new candidate, such as Joe Biden or John Kerry, could enter the race at the behest of the president.

While such a situation remains highly unlikely — something that Bill Clinton’s former political adviser was quick to point out — there remain huge doubts over Hillary Clinton’s ability to steer the Democratic Party towards unity and finally a victory over Donald Trump.

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