While Bernie Sanders' first event in Seattle was shut down by Black Lives Matter activists on Saturday, the Democratic presidential hopeful went on to draw record crowds at two other events over the weekend: 15,000 people at a second event in Seattle on Saturday, and a 28,000-strong crowd in Portland, Oregon on Sunday.

Sanders took the stage at the Moda Center sports arena Sunday night, home to the NBA's Portland Trail Blazers, which was filled to its 19,000 capacity. An additional 9,000 people gathered in overflow areas, according to The Washington Post.

The independent senator from Vermont has emerged as the leading alternative to Democratic presidential front-runner Hillary Clinton, whose favorability ratings have been tumbling in the polls.

By comparison, Clinton's biggest draw amounted to about 5,500 people, at her New York campaign kick-off in June, reports RT. No other candidate from any political party has drawn bigger crowds than Sanders, a self-described democratic socialist.

"Whoa. This is an unbelievable turnout," he said after walking on stage in Portland, according to a press release.

Sanders said his goal is to "reverse the four-decade decline of the American middle class and launch a grassroots 'political revolution' to take on the billionaire class."

He touched on a number of issues in the nearly hour-long speech, from economic and job proposals and civil rights issues to criminal justice reform. He promised a better life for the working class, a minimum wage increase to $15 an hour, expanded Social Security benefits and free college tuition.

"There is no candidate who fill fight harder to end institutional racism in this country and to reform our broken criminal justice system," he said.

His promise to go further than any other candidate to end racism in the U.S. was likely at least partially in reference to Black Lives Matter protesters who shut down his first event in Seattle on Saturday.

A dozen protesters stormed past barricades and jumped on stage as Sanders began to speak, taking the microphone from him and decrying Seattle as a racist city, also accusing the Sanders crowd of "white supremacist liberalism," as HNGN reported.

The protesters then demanded four-and-a-half minutes of silence to remember Michael Brown, a black man shot and killed by a white police officer last year in Ferguson, Mo.

Sanders held his composure and waited silently for 20 minutes before attempting to proceed with his speech, but he was interrupted once again and left the event for his next speech at the Comet Tavern on Capitol Hill.

"I am disappointed that two people disrupted a rally attended by thousands at which I was invited to speak about fighting to protect Social Security and Medicare," Sanders said in a statement. "I was especially disappointed because on criminal justice reform and the need to fight racism, there is no other candidate for president who will fight harder than me."

It was the second time in less than a month that Black Lives Matter activists interrupted Sanders, the last occurring at the liberal Netroots Nation conference in Phoenix in late July.