Washington (CNN) Many of the Democrats who've been urging stricter gun control legislation will join throngs of students Saturday as they gather in Washington and elsewhere for the "March for Our Lives" demonstration.

The event is expected to the biggest yet in a string of rallies and protests nationwide since a gunman killed 17 people at a high school in Parkland, Florida, last month. The shooting sparked an unprecedented wave of student-led activism calling for more gun control and school safety measures.

Saturday's march, which starts at noon, come a day after Congress passed a massive spending bill that included a large measure to increase security at schools, as well as legislation that would better enforce reporting to the National Instant Criminal Background Check System . The bill also aims to clarify that the Centers for Disease Control can conduct research on gun violence

Still, a number of other gun-related bills have been introduced and many Democrats, along with some Republicans, are working to keep gun violence a top priority in Congress.

"There's a long way to go and that's what these students are here for," Democratic Sen. Bill Nelson of Florida said Friday at a news conference with other lawmakers and activists.

Nelson worked with Republican Sen. Marco Rubio, also of Florida, to introduce legislation that would encourage states to adopt "red flag" laws , which would give authorities power to seize guns from those who pose a threat to themselves or others.

Rubio, who's been highly active in the gun debate since the Florida shooting, said Thursday at a news conference that his role is to legislate, rather than demonstrate.

"I am a legislator," Rubio said. "I pass public policy. Instead of marching, I should be acting, I should be passing laws," he said. "That doesn't mean you can't also do a march. I know some legislators will do that. But that's what I've been focused on. That's what I'll continue to focus on. That's why we are here, to announce this, because when we get back this is going to be the one thing that I think we can do next."

Republicans are largely keeping their distance from the rallies, though some are contributing in other ways. Rep. Carlos Curbelo, who's in an extremely competitive district in Florida and who introduced a bill this week to raise the age requirement for rifles and shotguns, announced he's donating $2,500 to help pay for transportation for Parkland students to the march in Washington.

House Minority Leader Nancy Pelosi will also remain in Washington for the event Saturday, as well as dozens of other House Democrats, and several more will take part in events in their districts, according to her office. Pelosi encouraged members to wear orange at the rally — a color affiliated with gun violence activism — and change their social media profile photos to show the text #NeverAgain and #EndViolence.

House Minority Whip Steny Hoyer will be in New Jersey for previously scheduled travel but his office said he plans to attend two sister events for "March for Our Lives" on Saturday while he's there.

Meanwhile, close to a dozen Senate Democrats say they plan to be at the march in Washington or meet with students around the march. They include Nelson of Florida, Sens. Ben Cardin and Chris Van Hollen of Maryland, Sens. Tina Smith and Amy Klobuchar of Minnesota, Sen. Pat Leahy of Vermont, Sen. Kirsten Gillibrand of New York, Sen. Jack Reed of Rhode Island, Sen. Tammy Duckworth of Illinois, Sen. Brian Schatz of Hawaii and Sen. Gary Peters of Michigan.

And roughly 20 lawmakers have confirmed they're taking part in events or meeting with students in their home states on Saturday: Senate Minority Leader Chuck Schumer of New York, Senate Minority Whip Dick Durbin of Illinois, Sens. Dianne Feinstein and Kamala Harris of California ,Sens. Chris Murphy and Richard Blumenthal of Connecticut, Sens. Elizabeth Warren and Ed Markey of Massachusetts, Sens. Jeanne Shaheen and Maggie Hassan of New Hampshire, Sen. Tim Kaine of Virginia, Sen. Sherrod Brown of Ohio, Sen Bob Casey of Pennsylvania, Sen. Mazie Hirono of Hawaii, Sen. Cory Booker of New Jersey, Sen. Tom Carper of Delaware, Sen. Maria Cantwell of Washington, and Sen. Bernie Sanders of Vermont.

This story has been updated to reflect additional developments.