Returning from a six-week summer recess during which several high-profile mass shootings left dozens dead, Democrats on Monday renewed pressure on Republicans to pass legislation to strengthen background checks for all firearm purchases.
"Americans are suffering," Senate Minority Leader Chuck Schumer, D-N.Y., said during a news conference at the Capitol Monday afternoon. "Background checks are the base from which we must do anything."
But when Senate Majority Leader Mitch McConnell outlined the upper chamber’s agenda for the next month, he previewed impending action on judicial nominations and appropriations bills – with no mention of gun control on the schedule.
Schumer urged McConnell and President Donald Trump to prioritize consideration of H.R. 8, the Bipartisan Background Checks Act of 2019, saying the president "has an historic opportunity to save lives."
"This bill is common sense," Schumer said. "The time to act is now."
McConnell said the Senate will start "right off the bat" to confirm Trump's various nominees for federal offices before shifting its focus to appropriations process.
"The American people know this is a highly charged political moment but they haven't sent us here to stage pitch battles or score political points," McConnell, R-Ky., said.
McConnell has previously said he does not intend to place any bill on the floor for consideration until he receives the president's blessing.
In the immediate wake of mass shootings last month in El Paso, Texas, and Dayton, Ohio, Trump said it was time "have some really meaningful background checks." But the president seemed to cool on the concept during the weeks since the shootings, instead putting the focus on mental health, such as red-flag laws.
Throughout the summer recess, the Trump administration engaged in a multi-agency effort to craft a range of potential options for the president -- even crafting potential legislative text, according to multiple officials familiar with deliberations.
Two weeks ago, the Department of Justice offered a set of recommendations to the White House. Attorney General William Barr has also privately urged the president to expand background checks to include all private gun sales.
One official confirmed to ABC News that Barr held a meeting with senior department officials last week to discuss potential policies aimed at preventing future mass shootings.
But as Congress returned Monday, it remained unclear when the White House would roll out a finalized proposal of what the president is ready to support.
A senior administration official said expanding background checks remained an option under consideration within the administration and that the White House intends to engage with stakeholders on Capitol Hill in the coming days.
Multiple officials said the timetable remains fluid, with one senior administration official saying the proposal could be expected sometime within the month of September.
House Speaker Nancy Pelosi said that the background check bill "isn’t radical" but is "just an expansion of what’s been successful already."
"There isn’t anyone whose political survival is more important than the survival of children," Pelosi, D-Calif., said alongside Schumer. "We are not taking no for an answer."
Pelosi and Schumer joined forces on a letter to President Trump earlier Monday, imploring him to exert sway over Republicans and give "political cover" in defiance of the National Rifle Association.
"The American people are crying out for their elected representatives to stop the epidemic of murder and mayhem that is shattering families and communities across the country. You are uniquely positioned to answer their call," the duo wrote. "We implore you to seize this moment when your leadership and influence over Republicans in Congress on the issue of guns is so critical."
While Democrats attempted to build pressure on Republicans to enact gun control throughout the recess, Sen. Chris Murphy, who has worked directly with the White House on gun control legislation along with a bipartisan handful of senators and their staff — warned "time is running out."
"I’m still negotiating in good faith to find a bipartisan proposal that will expand checks to cover more commercial sales and save lives, and I continue to take the president at his word that he wants the same thing," Murphy, D-Connecticut, stated. "But as each day goes by, it seems more likely that we're going to find ourselves back in a familiar place where 90 percent of the Americans who want more background checks are going to be disappointed once again."
In recent weeks, Murphy has given the talks a less than 50-50 chance of success.
Dayton Mayor Nan Whaley, in the nation’s capital with a group of mayors to lobby senators and the White House this week to act on gun control, pressed McConnell for an up or down vote on H.R. 8.
"We're meeting with the White House, with anyone who will listen to us, about what this has done to our community," Whaley, a Democrat, said during remarks at the Capitol. "There's an urgency about getting common sense reform gun legislation through the Senate."
ABC News' Mariam Khan and Alex Mallin contributed to this report