United States Democratic presidential candidate Bernie Sanders predicts he is more capable than party frontrunner Hillary Clinton of defeating presumptive Republican nominee Donald Trump.

Because of the more than 500 superdelegates who have pledged to Clinton’s campaign, she is considered to have nearly won the nomination.

However, a big win in California for Sanders in the state’s June 7 primary election would be a significant problem for the former secretary of state.

The U.S. senator from Vermont continued has been on a grueling schedule of campaigning up and down California in the past week, speaking to large and buoyant crowds in packed rallies.

In recent weeks, Sanders has been rapidly closing the gap with Clinton in California, with recent polls placing Sanders in a virtual tie with the frontrunner.

Even if Clinton gains enough delegates to capture her party’s presidential nomination, a loss in California would provide a sour and deflating end to her primary campaign.

It could also encourage Sanders to stay in the race through the party’s convention, at a time when many Democrats would be asking him to concede the race and join with Clinton in turning the party’s attention to defeating Trump.

According to an NBC News/SurveyMonkey tracking poll released last week, 37 percent of the participants said they “dislike” Clinton while 39 percent had the same feeling about Trump.

This is while 21 percent said they “hate” the former first lady and 24 percent expressed the same sentiment toward the New York billionaire.

Also, a Fox News poll released earlier this month found that majorities of voters feel both frontrunners lack strong moral values and will say anything to get elected.

Secret Service protects Sanders as audience members rush stage

Elsewhere, members of Sanders's Secret Service team surrounded him as audience members at a rally on Monday tried to rush the stage, according to multiple reports.

At least three people were led away by security at the Oakland, Calif., event, held eight days before the state's June 7 presidential primary.

Sanders was unharmed when agents leaped on the stage and pulled him away from his microphone as the unidentified attendees pushed through audience barriers.

A protester also tried to jump onto Sanders's stage in March during a rally in Ohio.

Sanders was spotted later on Monday in Oakland at Game 7 of the Golden State Warrior's Western Conference Finals against the Oklahoma City Thunder.

Trump aide defends bringing up judge's 'Mexican' heritage

The development follows as Donald Trump spokeswoman Katrina Pierson on Monday defended the presumptive GOP (Grand Old Party) presidential nominee for calling a California judge overseeing a fraud case against Trump University a “Mexican” and a “hater.”

On Friday, Judge Gonzalo Curiel rejected arguments from Trump and called for documents related to the not-defunct university to be unsealed. In an interview on CNN, Pierson pointed to his membership in a Latino lawyers group in California to show he is anti-Trump.

At a rally earlier this week, Trump said Curiel should not have scheduled a trial for the suit against Trump University in November.

When CNN host Alisyn Camerota pointed out that Curiel was born in America, Pierson continued to link the judge with protests taking place outside Tump rallies. She said she doesn't know if the judge is Mexican or not, but people need to identify who is protesting and what they are doing.

“Well, it's because of what we see outside of these rallies, these anti-Trump rallies, these criminal rallies, these criminal protesters out there defacing property and attacking police officers,” Pierson said.

“They're doing so under the guise of an anti-Trump protest, with their Mexican flags, and La Raza and this judge is connected to that.”