Sen. Bernie SandersBernie SandersPoll: Biden leads 2020 Democratic field by 15 points, followed by Sanders and Warren Warren introduces bill to cancel student loan debt for millions Democrats, advocacy groups urge Pompeo to abolish new 'unalienable rights' commission MORE (I-Vt.) attracted another huge crowd at a rally for his presidential campaign in Los Angeles on Monday night.

The Sanders campaign, citing Los Angeles Memorial Sports Arena officials, said 27,500 people were inside the venue or in an overflow area outside to hear Sanders speak.

Actor and comedian Sarah Silverman introduced Sanders at the event.

“I give you, if we’re all very smart and a little bit lucky, the next president of the United States,” she said, according to remarks provided by the campaign.

Monday night’s event caps a three-day West Coast swing for Sanders that saw him pull record crowds.

On Sunday night, 28,000 people attended a Sanders rally in Portland, the largest crowd so far for any political event in the 2016 cycle.

On Saturday, an estimated 15,000 people turned out to see Sanders in Seattle.

Sanders also landed his first major union endorsement on the trip, with the National Nurses United announcing Monday they would back his Democratic bid for the White House.

Hillary ClintonHillary Diane Rodham Clinton5 things to know about Boris Johnson Trump says Omar will help him win Minnesota The Hill's Morning Report — Trump applauds two-year budget deal with 0 billion spending hike MORE maintains a huge lead over Sanders in national polls and remains the heavy favorite to win the party's nomination.

Still, Sanders has energized grassroots liberals and emerged as the biggest threat to Clinton for the Democratic nomination. The crowds he’s attracting on the campaign trail are staggering in size for an underdog in an off-year.

In addition, Sanders has made gains in the polls in New Hampshire, the first-in-the-nation primary state, where he only trails Clinton by 7 points, according to the RealClearPolitics average of polls.