Senate Minority Leader Charles E. Schumer (D-N.Y.) walks with protesters during a demonstration demanding gun control in New York City on March 24. (Shannon Stapleton/Reuters)

The rallies against gun violence across the United States on Saturday kept politicians offstage, and instead prioritized the voices of students who have survived mass shootings.

But politicians, most of them Democrats, cheered them on from the crowd. Democratic leaders from both houses of Congress participated in the marches, along with dozens of colleagues and candidates who are running for office in 2018. Their message: Listen to the students, and do what they say.

“I marched for two hours with the students in New York and came away inspired by their enthusiasm, steadfastness and focus on electing representatives who support their goals,” said Senate Minority Leader Charles E. Schumer (D-N.Y.) in a statement. “The only thing standing in the way of achieving their goals is the president.”

In Washington, where the March for Our Lives rally was held, the only adults who shared the stage with students were musicians and celebrities. Politicians were given little time to speak in other cities, like Atlanta, where Rep. John Lewis (D-Ga.) told marchers he was ready to get arrested again — he has been arrested five times as a member of Congress — to fight for gun-control legislation.

“We are never too young, we are never too old, to march, to speak out, and to find a way to do something about gun violence,” Lewis said. “Vote like you’ve never voted before.”

Where politicians were offstage, marchers didn’t need to be sold on politics. Chants of “vote them out” rang in Washington and at other marches. In Houston, some marchers chanted “Where’s Ted Cruz?” as they passed a building where he kept a constituent office. HeadCount, an organization founded to register voters at concerts and festivals, dispatched volunteers to sign up marchers who were old enough to vote.

“We’re going to put in place your program,” said Rep. Keith Ellison (D-Minn.), the deputy chair of the Democratic National Committee, in a short video. “But it’s going to take us raising public sentiment, and you are doing that right here, right now.”

On Twitter, congressional Democrats shared messages of support, videos of the crowds they saw, and the names of gun-control bills they wanted to pass.

“Every great social change movement in this country’s history has been led by young people,” tweeted Sen. Chris Murphy (D-Conn.), who joined the Senate shortly after the 2012 massacre in Newtown, Conn.

Other Democrats met with students before the marches, then got out of their way. In Boston, Sen. Elizabeth Warren (D-Mass.) talked with student survivors of mass shootings, then told reporters that “they have figured out that they do a lot better when they organize and lift their voices together.”

In Washington, Sen. Brian Schatz (D-Hawaii) met with students who traveled from his state, then tweeted some of his favorite protest signs, such as one that read “girls’ clothing is more regulated than guns in America.” In Los Angeles, Mayor Eric Garcetti, who is seen by some in the party as a potential presidential candidate, challenged Trump directly to “get with the program . . . or get the hell out of the way.”

Candidates challenging each other in primaries declared their solidarity with the students, too. California State Sen. Kevin de León, who is challenging Sen. Dianne Feinstein (D-Calif.) this year, met with students and joined a march. Feinstein tweeted that she’d “been fighting to get weapons of war off our streets and out of our schools since I was first elected,” and had never seen “this passion, this energy, this determination” for the cause before.

There was less praise for the marches from Republicans. The president, who had been criticized for joking that the Jan. 20 Women’s March was held to honor him, did not personally comment on Saturday’s events. Instead, White House spokeswoman Lindsay Walters issued a statement about the protesters.

“We applaud the many courageous young Americans exercising their First Amendment rights today,” Walters said. “Keeping our children safe is a top priority of the President’s.”

No Republican leader in Congress commented on the March, though some Wisconsin students have planned a four-day walk from Madison to Janesville to pressure House Speaker Paul D. Ryan (R-Wis.). Rep. Mia Love (R-Utah) was one of few Republicans who did have a reaction, writing in an op-ed for the Deseret News that Congress needed to address “school safety” in some way.

“We must listen carefully to our students as they express the real problems they face,” Love wrote. “They have a story to tell, and our deeper understanding can very well save their lives.”

Democrats were more outspoken about what they wanted: legislation to tighten background checks, restrict the sales of some magazines, and a restored ban on “assault weapons.” In an interview at the Washington march, Sen. Bill Nelson (D-Fla.) said most Americans wanted what the students were marching for.

“The polls will show, in my state of Florida and across the nation, that people don’t want big long clips of many rounds, and they don’t want assault rifles out there to conduct these massacres that we’ve seen,” Nelson said.

Onstage, in Washington and elsewhere, the students were happy to draw distinctions between the parties.

“Stand for us or beware,” said Cameron Kasky, a Marjory Stoneman Douglas High School student who challenged Sen. Marco Rubio (R-Fla.) during a CNN town hall to stop taking donations from the National Rifle Association. “The voters are coming.”

Libby Casey and John Wagner contributed reporting.