To get one of 1,400 seats at Donald Trump’s rally here Thursday night, hundreds and hundreds of people waited for hours in the cold and then had to answer a question like this: Do you support Donald Trump?

Anyone who did not answer with some version of “yes” was not allowed inside. That included undecided voters and those simply looking to learn about Trump’s positions. And anyone showing any trace of supporting Bernie Sanders — the former mayor of this liberal town who is now a Democratic presidential candidate — was definitely not allowed in.

Trump explained his thinking in a statement: “We have more than 20,000 people that showed up for 1,400 spots. I’m taking care of my people, not people who don’t want to vote for me or are undecided. They are loyal to me and I am loyal to them.”

The yes-or-no question was quickly compared to the strategy Trump has proposed for screening Muslims trying to enter the country if he were to temporarily ban them. At first, the pledge seemed to work, and Trump presided over an unusually calm and collected rally crowd inside the Flynn Center for the Performing Arts, a historic 1930s Art Deco theater.

But about 20 minutes into his 70-minute speech, a woman wearing a headlamp and a sign reading “Dump Trump” came marching down an aisle. She was quickly escorted out, and Trump provided this assessment: “That was a very mild protest.”

Protesters are escorted from Trump's event at the Flynn Center for the Performing Arts Thursday. (Scott Eisen/Getty Images)

A series of other interruptions followed, dominating the evening. Trump mostly stuck to his regular talking points, although he seemed to take a new stance on gun access, saying that he wants to ban gun-free zones at schools.

Aides to the candidate did not respond to requests for more details on that proposal.

From the theater balcony came chants of “Bernie! Bernie! Bernie!” As about half a dozen protesters were walked out, Trump’s supporters responded “Trump! Trump! Trump!”

As more of these outbursts occurred, paranoia seemed to set in among the crowd, and some Trump supporters tried to spot potential intruders before they acted up.

In one case, a handful of supporters towered over a young woman in a winter cap seated in the crowd and yelled, “Out! Out! Out!” As police pulled the woman out of the theater, she pleaded, “I didn’t do anything!”

Later, two women stood, pointed at Trump and repeatedly shouted, “Get Trump out!” They were removed from the theater.

It was often difficult to understand what the protesters were shouting, as they were quickly drowned out by Trump’s supporters. Sometimes Trump didn’t stop talking as the outbursts quickly came and passed. At other times, he mocked the protesters or marveled at how his rallies are so much more interesting than those of his rivals.

Republican presidential candidate Donald Trump screened entrants to his Jan. 7th rally in Burlington, Vt., but that didn't stop protesters from getting in. Watch how he handled the more than half-dozen disruptions to his speech. (Jenny Starrs/The Washington Post)

Once, he suggested confiscating the coats of some hecklers and throwing them out into the cold.

Trump said that he expected this sort of reception — after all, he was trolling Sanders in his own town.

He mentioned Sanders a few times during the rally, at one point mocking the senator for allowing two Black Lives Matter activists to publicly interrupt him and take over his microphone.

“Oh, would I love to run against Bernie,” Trump said at one point, as the crowd cheered. “It would be a dream come true.”

Sanders responded to Trump’s eagerness during a conference call Thursday night with thousands of members of Democracy for America, a progressive group that has endorsed Sanders and is based in Burlington. Sanders predicted he would beat Trump decisively in a general election and ticked off several digs the Democrat has taken at the Republican front-runner lately, including calling him a “pathological liar.”

“It would be a dream come true for me as well,” Sanders said. “I would love, love, love to run against Donald Trump.”

Trump’s campaign gave away nearly 20,000 free tickets to the rally, many of which were snapped up by Sanders supporters, Trump haters or others who wanted him to have an empty theater. The Burlington Police Department expected about 6,500 people to show up — still far more than the number of seats in the small theater.

“If Phish was holding a free concert at the Flynn and gave away 20,000 free tickets, we would cancel the event out of public safety concerns,” Burlington Police Chief Brandon del Pozo told the Burlington Free Press. “We are committed to accommodating the campaign because political speech is the very essence of the First Amendment.”

The line started early in the morning, and those standing together bonded, holding spots for bathroom breaks and pizza runs.

Brothers and lifelong Burlington residents Mike and Rod Dion arrived about 8 a.m. Nine hours later, both took the Trump pledge, saying they “absolutely” supported the candidate, although both say they still aren’t absolutely sure.

But they are positive they want President Obama out of office. Once inside the theater, Rod Dion, 60, changed into a red tank top featuring a drawing of the president smoking dope.

Both worked manufacturing jobs, and at one point both were laid off when the factory where they worked moved overseas.

In explaining what it’s like to be a Republican in such a liberal area, Mike Dion, 64, noted: “Bernie Sanders, this is where he is from.”

“Well,” Rod Dion said. “He’s not from here. He’s from New York.”

He continued: “It was nice here, then he brought in a lot of freaks, he brought in people from out of state and our state has changed. . . . Our whole state has actually changed because of Bernie Sanders.

“It’s like a freak show here,” he said.

Katie Zezima and John Wagner in Iowa contributed to this report.