NEW YORK — Dozens of liberals showed up at a Brooklyn synagogue Monday night for a chance to question Senate Minority Leader Charles E. Schumer about the Supreme Court, immigration and resistance to President Trump.

Instead, the New York Democrat had to phone it in — quite literally — as a mechanical problem left his plane grounded in central New York some 200 miles away, forcing the last-minute cancellation of his town hall.

Yet that didn’t deter the activists from peppering him with questions, and the senator spent an hour answering.

Could Schumer ensure that every Democrat would line up against Trump’s nominee to replace Supreme Court Justice Anthony M. Kennedy? Was the senator prepared to put civility aside and be ruthless to prevent the court’s shift to the right?

“This is not a fait accompli,” Schumer said on the conference call. He said that Democrats would have little success in delaying the vote on Trump’s nominee and should focus on driving home the point that the future of abortion rights and the Affordable Care Act depend on the pick.

Some in attendance said they simply wanted to commiserate with other New York liberals after days of unrelentingly bad political news and search for outside-the-box solutions. Could Republican Sen. John McCain (Ariz.), who at times has criticized President Trump, be persuaded to join the Democratic Party?

“We need a person who will physically put their body on the tracks,” said Tracie Gardner, 53, as she joined the crowd in a chant of “Whip the vote!” “This decorum and civility — we don’t have the luxury for that.”

McCain, in fact, has not been in Washington since December as he battles brain cancer.

With progressives panicked over a range of issues — from the separation of migrant families at the U.S. southern border to the battle over a successor to Kennedy — Schumer, the top Senate Democrat, got an earful from members of his party’s base Monday night.

Both on the call and at the event, people spoke in apocalyptic terms about the country’s future and demanded to know why Schumer and national Democrats were not putting more pressure on Trump and congressional Republicans.

“We are in a gunfight and we have a butter knife,” one caller said.

The event underscored the enormous pressure Democrats are facing as they struggle to satisfy calls for aggressive action while trying to ensure the reelection of centrist Democrats in the states Trump won handily in 2016, such as West Virginia, North Dakota and Indiana.

Democrats have found themselves at odds over how far they should go in their efforts to oppose Trump and his policies.

Some, such as Rep. Maxine Waters (D-Calif.), have called for members of the public to aggressively confront administration officials wherever they go. Others have called for a more restrained approach, urging supporters to focus on making their voices heard at the ballot box in November.

One of those chastising Waters — albeit not by name — was Schumer. “No one should call for the harassment of political opponents. That’s not right. That’s not American,” Schumer said in a Senate floor speech last week.

Schumer has sought to channel the anger of Democratic activists in recent days. In a New York Times op-ed published Monday, he urged members of the public to contact their senators and tell them not to vote for a Supreme Court nominee from Trump’s list of 25 names.

Schumer also sent out tweets on the topic Monday morning, taking aim at the record of one of Trump’s potential Supreme Court nominees, Amy Coney Barrett.

If chosen, Schumer wrote, Barrett “will be the deciding vote to overturn Roe v. Wade and to strike down pre-existing conditions protections in the ACA.”

The town hall was organized by Indivisible Nation BK, a grass-roots liberal group affiliated with the national group Indivisible, at a synagogue just a few blocks from Schumer’s Brooklyn home. About 100 people took their seats, and the event went ahead without the senator.

Activists vowed to keep the pressure on Schumer and led chants of “Reschedule Chuck.”

“We are talking about a president who did not win the popular vote and we’re going to give him two Supreme Court justices who can shape the court for the next 40 years?” asked Kathryn Miles, 62. “I don’t know what we should do but we should at least be vocal.”

At one point, organizers held up a cardboard cutout of the senator’s face and torso and said that in his absence, constituents could address “Cardboard Chuck.”

Sherese Jackson, 41, a Brooklyn schoolteacher who is part of Indivisible Nation BK, asked why national Democrats were not doing more to support black women running for Congress.

“Will you and the DCCC commit to endorsing and financially supporting non-establishment women with their upcoming elections?” she asked before the cheering crowd.

Most of the focus was on the future of the Supreme Court. Trump has said he would announce his nominee next week, and it is widely expected that he will choose a judge who will move the court further to the right, especially on social issues such as abortion and same-sex marriage.

Kennedy became a justice in 1988 and had joined the court’s liberal wing on several key cases, including the 2015 ruling to allow same-sex marriage.

“We need united Democrats. There can’t be anything less than that,” said Liat Olenick, a leader of Indivisible Nation BK.

Indivisible said that it had been lobbying Schumer’s office for a year in hopes of setting up a meeting with constituents. A spokesman for Schumer said that the senator’s office hoped to reschedule the town hall for later in the week.