By LISA MASCARO
AP Congressional Correspondent

WASHINGTON (AP) - Facing criticism that the Senate has become little more than what one member calls an "expensive lunch club,"

The Kentucky Republican has promised a "Grim Reaper" strategy focused on burying House Speaker Nancy Pelosi's legislative priorities, but without a robust GOP agenda it could prove unsatisfying for lawmakers facing restive voters ahead of 2020 elections.

President Donald Trump has not fully explained what he would like to see Congress accomplish, particularly on gun control, and McConnell is reluctant to venture too far, beyond confirming the White House's administrative and judicial nominees.

That leaves big-ticket legislative victories highly unlikely as Pelosi's Democratic House churns out bills, the Republican Senate takes a pass, and the legislative calendar folds into campaign season. Democrats call it McConnell's legislative "graveyard."

Pelosi and Senate Democratic Leader Chuck Schumer in a letter to Trump released Monday urged the president to intervene and take the lead on gun violence legislation.

"Your urgent, personal intervention is needed to stem the endless massacres of our fellow Americans by gunfire," the top Democrats wrote to Trump. "We implore you to seize this moment when your leadership and influence over Republicans in Congress on the issue of guns is so critical. Please do not squander it by acceding to NRA-backed proposals or other weak ideas that will do nothing to stop the continuing, horrific spread of gun violence."

One test of voter mood will come in Tuesday's special election in North Carolina , where the Democrat for an open House seat, Marine veteran Dan McCready, faces Republican Dan Bishop, in a contest both parties see as toss-up. Trump is swooping in for a rally to push voters to the polls.

As legislating makes way for campaigning, Sarah Binder, a professor at George Washington University, said by email, "The challenge for both parties though is that they really do need something to deliver to voters in 2020."

Trump does want Congress to pass the new U.S.-Mexico-Canada trade deal. And Congress needs to fund the government by the end of the month or risk another federal shutdown. But the president roiled talks by shifting $3.6 billion from military projects for the border wall and fallout continues over migrant detentions. Questions of impeachment hover.

Gun regulation, perhaps more than other issues, is putting pressure on the Senate to act.

August was bookended by devastating mass shootings across three cities that killed dozens and left scores more injured. Big business is stepping in to fill the void, with Walmart becoming the latest to announce limits on some ammunition sales. While a House-passed background checks bill stalled in the Senate, McConnell says he expects the White House to soon offer next steps.

"We're under discussion about what to do on the gun issue," McConnell said on the Hugh Hewitt radio show.

McConnell has made it clear that he won't make any moves without Trump's commitment to sign the bills into law. But the president has flip-flopped on guns, first suggesting he'd be open to background checks legislation or other measures to try to stem gun violence, only to backtrack after speaking to the National Rifle Association and others in the gun lobby. The Senate leader is trying to avoid a politically uncomfortable situation of Republicans joining Democrats to pass bills, only to have Trump reject them.

Against this backdrop, McConnell outlined what he must see before considering any guns legislation: "If the president is in favor of a number of things that he has discussed openly and publicly, and I know that if we pass it it'll become law, I'll put it on the floor."

Senators from both parties have been meeting privately and with the White House on possible areas of agreement. Trump said he was talking with Sen. Joe Manchin, D-W.Va., who has a bipartisan background checks bill with Republican Sen. Pat Toomey of Pennsylvania that has failed in previous votes.

Toomey, who said he has spoken several times with Trump over Congress' summer break, said the president has been more consistent in his support for expanding background checks than people give him credit for.

"The president has a real interest in doing something in this area," Toomey said. Several Republican senators are also now more interested but, he said, "it's hard to say how this will turn out."

Sen. Chris Coons, D-Del., who is also involved in talks, including with White House senior adviser Ivanka Trump, said he is encouraged that the president may be interested in more narrow efforts, including his bipartisan bill with Toomey. It would require federal authorities to alert state officials when people trying to buy firearms are denied by the National Instant Criminal Background Check System.

Before lawmakers left town for the six-week summer recess, senators from both parties bemoaned the way the world's most deliberative body has become what Sen. Chris Murphy, D-Conn., calls a pricey lunch club. He too is working on gun legislation.

"I miss the Senate that used to spend the odd-year really legislating and really working on policy," said Sen. Susan Collins, R-Maine, who is up for reelection. "We seem now to be caught up in a constant campaign and that is I think a disservice to the American people."

Sen. Lamar Alexander, R-Tenn., and chairman of the Senate's health committee, is working on a bipartisan package of bills to lower health care costs. He said there's more happening than the public often sees on the endless loop of political and partisan fighting.

"We always have those two screens going on," said Alexander, who is retiring at the end of his term. "While things could be much better in the United States Senate, there's a lot being done."

McConnell has taken pride in stopping Democrats' agenda and is incorporating the "Grim Reaper" role in his own reelection campaign for 2020. The GOP leader, who suffered a fractured shoulder in a fall in early August, has been recovering at home in Kentucky but is expected to return to open the Senate on Monday.

Asked about the Senate agenda for fall, his office had little to add. A spokesman sent a memo that included a long list of administrative nominees up for Senate confirmation.

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Associated Press writers Andrew Taylor and Matthew Daly contributed to this report.

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