Manchin says former NRA staffer's background check app proposal could derail talks

Senators are waiting to hear from President Trump about what he'll support.

capitol hill -- It's not often that Joe Manchin gets angry, at least not publicly, but a flash of anger bubbled up Monday as the West Virginia Democrat lashed out -- unprompted -- at a former NRA staffer now working at the White House who has become deeply involved in the ongoing bipartisan gun control talks between senators and President Donald Trump.

Michael Williams - now a senior administration official who worked as an NRA lawyer -- and before that for nearly two years with an association representing gun silencer manufacturers -- attended a White House meeting last week involving Manchin and two of his fellow Senate negotiators - Pat Toomey, R-Penn., and Chris Murphy, D-Conn.

Manchin, speaking to reporters at the Capitol Monday night, voluntarily brought up Williams, visibly annoyed that the staffer had "come in at the last minute" with an idea for an app to expedite background checks, something that the senator said “would be very detrimental to what we’re trying to do right now.”

Momentum for a major gun control compromise appears to be slowing after a summer marred by a spate of mass shootings, and tension is mounting as days pass without a decision from the president as to what he will support, if anything, in the way of legislation.

Democrats are trying to keep up pressure on the president to come to a decision soon. House Speaker Nancy Pelosi, D-Calif., and Senate Democratic Leader Chuck Schumer, D-N.Y., called the president over the weekend, and in the 11-minute phone call, the duo pushed a House bill that mandates universal background checks, something Republicans have opposed.

Manchin, Toomey, and Murphy - along with their staffs - have spent hours in talks with the White House over the past several months designed to craft legislation that could garner Trump's signature. Toomey quipped recently that he spent his month-long August recess singularly focused on this topic.

“Why is this one guy bringing this up right now?" Manchin bristled, saying that the Department of Justice has concerns about the app, as well. "Why is this one guy adamantly wanting one thing done which makes no sense right now?”

Manchin, a moderate and sometimes Trump ally, said he told the White House he is happy to fund a year-long study of the app, but he said there are just too many questions and not enough time to figure it out.

“Throwing in something like a new app for how you’re going to do a background check? Okay, maybe, I don’t know. But it’s not worth saying we’ve got to do this right now, because you’re saying something’s broke. [The background check system] is not broke," Manchin said, adding, "I’m concerned, and DOJ’s concerned about how it would impede their investigations.”

At the White House meeting at which Williams presented the app idea, Manchin said he and the former NRA staffer got into it, with the senator saying Williams “got very vocal, and I got very vocal.”

The White House has not responded to ABC News' request for comment.

As Washington awaits a presidential decision, and all sides of the debate lobby Trump, Democrats, and some Republicans like Toomey, are trying to keep up pressure for expanding background checks. This as a recent ABC News poll found overwhelming support - 89 percent of Americans - for expanding background checks on all commercial sales, including gun shows and private sales. Sens. Manchin, Toomey, and Murphy have been pressing the President to embrace their legislation that does just that.

On Tuesday night, Sen. Murphy will lead more than 20 of his Democratic colleagues in speeches highlighting the impact of gun violence.