WASHINGTON — Survivors of gun violence and families of victims whose lives were taken in mass shootings are taking Senate Democrats to task for failing to champion pending legislation to address gun violence that passed the U.S. House last month.

In a letter being sent to the elected officials, and shared with NBC News, the group of about 200 are asking Democrats to "fight for us," or do a better job of elevating the issue of gun violence, specifically the House legislation that tightened the nation’s background check system.

The list of those being singled out by the plea includes Democrats who are actively running for president, like Sens. Kamala Harris of California and Cory Booker of New Jersey, who also serve on the Senate Judiciary Committee, which has jurisdiction over gun-related legislation.

"We did our part," writes the group, which includes parents of children killed in Parkland, Florida, at Virginia Tech and in Aurora, Colorado. Fred Guttenberg, the father of Jaime Guttenberg, who died in Parkland, is delivering the letter to senators.

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"We are calling on every single senator who supports background checks to go to the body of the Senate and begin discussing the bold policies we need to build a future with fewer guns — and not stop until there is a vote," says the letter. "This is doubly true for the senators who are running for president. They must prove to us that they can lead by doing everything in their power to get this through the Senate."

The group faults the Democratic senators for not delivering floor speeches, let alone trying to advance the legislation through the Judiciary Committee. The House bills would tighten U.S. laws, including requiring background checks on all commercial gun sales, including those at gun shows and over the internet.

"This letter is the very first step in a monthslong effort to make progress in the Senate," said Igor Volsky, director of Guns Down America, the group that helped organize the letter. It "is addressed to the self-proclaimed champions of background checks. If you're going to call yourself a champion on this issue, you better act like it," he said.

The coalition kept a log documenting inaction and compiling the number of times the Democratic senators issued press releases or raised the gun safety issue on Twitter or Facebook following the House vote. According to a summary, only one Democratic senator (Chris Murphy of Connecticut), issued a press release after the House vote; 13 Democrats tweeted and 10 mentioned it on Facebook.

Sen. Mitch McConnell of Kentucky, the Republican leader, is highly unlikely to allow the bill to come for a vote and President Donald Trump has vowed to veto it should it ever pass.

Instead of considering the House-passed bills, Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., has said the committee will consider “red flag” laws in a March 26 hearing. Supported by the National Rifle Association and the White House, those bills allow courts to take away firearms from potentially dangerous individuals after warnings from police officers or family members.

Yet the group argues a sustained spotlight on the issue could put pressure on vulnerable Republicans up for re-election in 2020, like Sens. Cory Gardner of Colorado and Martha McSally of Arizona.

Other co-signers include Lori Haas, whose daughter was shot twice at Virginia Tech; Manuel Oliver, father of deceased Parkland student Joaquin Oliver; and Sandy Phillips, whose daughter was shot and killed in Aurora, Colorado.

Activists seeking to elevate the gun violence issue in recent years made significant gains in 2018.

Many of the candidates who ran openly on a platform to curb gun violence won, even in traditionally Republican areas like Texas. Victorious candidates included Rep. Lucy McBath of Georgia, who lost her son, Jordan Davis, in 2012.

Volsky says the 2018 election should have sent a clear message, especially to many Democrats who for the past two decades have shied away from the issue during elections.