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

Although Mrs. Clinton is close to winning the party's nomination, Sanders, a left-wing politician, is pressing on with his campaign. Experts say 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 point I will be making to the Democratic National Convention is that in virtually every single poll, we do better against Donald Trump than secretary Clinton,” Sanders said Monday in Oakland, California.

“So if we want a campaign that will make sure the disaster that is Donald Trump does not become president, we are that campaign,” he added.The US senator from Vermont continued: “The pundits, in their infinite wisdom, said this would be a fringe campaign ... a year later, we have won primaries in 20 states.”

Sanders 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.