WASHINGTON — On the fourth anniversary of the school shooting in Parkland, Florida, survivor David Hogg delivered a tough message to Democrats: If you fail to use your power to act against gun violence, you’re no better than the National Rifle Association.

“Many people do not want to hear this. The fact of the matter is if you say you support gun violence prevention legislation, you get elected on that and you do nothing about it, I don’t see you as any better than the NRA,” Hogg, a co-founder of March For Our Lives, said on MSNBC. “Blood is on your hands, too, because people are dying because of your inaction.”

His remarks Monday were a harsh warning to Democrats who control the White House and both chambers of Congress and have been unable to deliver on their promises to toughen gun laws. Two bills to beef up background checks have passed the House but are stymied by Republican opposition in the Senate, where 60 votes are required to pass most bills.

Advocates used the four-year mark of the Parkland massacre this week to push the Biden administration to take further executive actions on guns and pick a new director for the Bureau of Alcohol, Tobacco, Firearms and Explosives. They also want Congress to use the filibuster-proof budget process to fund violence prevention programs and study the issue.

Igor Volsky, the executive director of Guns Down America, a group advocating for fewer firearms, said President Joe Biden’s actions “pale in comparison to what he promised” in his 2020 campaign, when he ran as a candidate uniquely situated to defeat the NRA.

“We understand the structural difficulty and systemic obstacles to making progress on guns,” Volsky said. “The question we should be asking in light of catastrophic increases in gun deaths is: Has the president done everything in his power to address gun violence? Absolutely not. He’s left too many pieces on the table.”

Volsky said he has told Cedric Richmond, a senior adviser to Biden, and other officials that “the standard” for delivering on guns is to put “the same amount of work and priority the administration put into Covid relief, infrastructure and passing Build Back Better.”

“I’ve yet to see the president really put his shoulder into this issue.”

In a statement this week marking the Parkland anniversary, Biden touted his efforts to curb “ghost” guns and go after firearm dealers “who wilfully violate the law.” He called on Congress to approve $500 million for gun violence prevention. In a recent trip to New York, Biden framed his gun violence campaign as an effort to combat rising crime, which Republicans have sought to weaponize politically against Democrats in the midterm elections.

“We can never bring back those we’ve lost,” Biden said. “But we can come together to fulfill the first responsibility of our government and our democracy: to keep each other safe.”

The Biden administration has yet to finalize its rule cracking down on “ghost” guns, prompting some Democratic senators to publicly call on the president to get it done. And Biden hasn’t nominated a pick for ATF after having withdrawn the nomination of David Chipman in September.

“I think the White House can do more,” said Sen. Chris Murphy, D-Conn., a Biden ally and outspoken proponent of tougher gun laws. “I’ve been talking to the White House recently about some additional steps that they can take — including executive orders, finalizing the ghost gun order and appointing a new ATF director. So there’s a series of steps the White House can take in the next 30 to 60 days that will show the advocates they’re serious.”

Overall, the reaction from gun control activists has been mixed. While some, like Hogg and Volsky, publicly pressure Biden to do more, others have sought good relations with the White House and fear that speaking out in critical terms could close off pathways to advance their goals.

The House has passed two bills to extend background check requirements for commercial sales and toughen up the three-day rule for firearm transfers. Biden has endorsed the bills, among others, like measures to ban military-style assault weapons.

But the bills have languished in the Senate, where Democrats hold a slim 50-50 majority with the vice president’s tiebreaking vote and face fierce Republican opposition to new gun limits. They have failed to curtail the 60-vote rule because of two defections in their ranks, all but choking off a path in the chamber.

The most promising bipartisan negotiation to break the impasse, between Murphy and Sen. John Cornyn, R-Texas, collapsed last year amid irreconcilable differences over how to classify dealers who are in the firearms business as opposed to being private sellers.

Senate Majority Leader Chuck Schumer, D-N.Y., promised a vote on the House-passed bills last March. Asked this week when that vote will happen, he replied: “Senator Murphy has been trying to work with Republicans to get 60 votes. He hasn’t given up on those efforts, although they’ve not gotten that far.

“But we’re going to keep pursuing background checks. I believe in that very, very strongly.”

Murphy said he has also talked to the administration about taking regulatory steps to “clarify which kind of dealers are engaged in the business” and thus required to conduct background checks. “Some of that can be done through executive actions, as well,” he said.

Cornyn cautioned against that approach and insisted that there is still hope of winning 60 votes on measures to tackle gun violence.

“Executive orders obviously are not ideal. They can be challenged in court, and they probably will be,” he said. “It’s sort of an admission that they’re not willing to do the hard work of building bipartisan consensus.”

Murphy argued that it’s “hard to explain” why Democrats have power and are refusing to act. “We don’t have an operating majority in the Senate,” he said. “You’re explaining rules and inside baseball. The kids on the front lines of the anti-gun-violence movement don’t want to hear that.”

The background check measures are popular, and the cause has passionate support from Democratic voters, including suburbanites and parents who have embraced the issue as mass shootings become a regular feature of American life. Many of those college-educated voters stopped voting Republican in recent cycles, partly because of former President Donald Trump’s takeover of the party, and voted to elect Democrats.

But advocates say that in the fall election, in which Democrats face major challenges in mobilizing their base and holding on to swing voters, failure to make good on those promises could backfire.

“There’s a great political cost to overpromising and underdelivering,” Volsky said, faulting Democrats for thinking they can “simply get away with promising you the moon when they need your vote and then turn around and say: You just don’t understand these complicated politics.”