Former Secretary of State Hillary Clinton’s effort to close out the Democratic race may be going awry, as a new poll shows she’s in danger of losing California to Sen. Bernie Sanders.

According to a new Fox News poll conducted April 18-21, Clinton has the support of 48 percent of likely Democratic primary voters, while Sanders is right behind with 46 percent. That’s the closest margin yet between the two in the state, which awards more delegates to the Democratic National Convention than any other.

Clinton holds a substantial delegate lead over Sanders and remains heavily favored to win the Democratic nomination, and a narrow loss in California wouldn’t change the situation much since Democratic primaries award all delegates proportionally.

California is the last state on the Democratic calendar and losing it could drain much of Clinton’s momentum going into the Democratic convention. At least in theory, a major loss could even induce some Democratic superdelegates to consider backing Sanders, which is likely the only plausible way for him to nab the nomination at this late stage.

Meanwhile, in the Republican race, Donald Trump holds a gargantuan lead over his remaining Republican rivals, polling at 49 percent support compared to 22 percent for Sen. [crscore]Ted Cruz[/crscore] and 20 percent for Ohio Gov. John Kasich. Trump’s 27-point advantage represents a huge boost over other recent polls, which have given him a lead of seven to 18 percentage points.

Trump’s massive lead could be critical, as he is still fighting hard to secure a majority of delegates prior to the Republican National Convention. California awards its delegates on a winner-take-most basis, where the winner of each congressional district takes three delegates. Trump’s big lead increases the chance that he will sweep every district in California, which would give him an excellent chance of reaching the critical 1,237-delegate threshold.

Despite Trump’s big lead, Fox’s poll also found that Republicans who don’t support him are deeply dissatisfied and may consider voting third party or not voting at all. Thirty percent said they would consider a third-party vote in a Clinton v. Trump match-up, while 12 percent said they wouldn’t vote.

The story was similar for Sanders supporters. In a Clinton v. Trump match-up, 36 percent said they’d consider a third party and nine percent said they wouldn’t vote at all.

The poll had a sample size of 483 Republicans and 523 Democrats. Each sub-group’s survey had a margin of error of plus or minus four percentage points.

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