Donald Trump met behind closed doors with about two dozen congressional allies and Republican influencers at a Washington D.C. law firm Monday for what attendees described as a session to discuss political strategy and "party unity."
Several lawmakers, many of whom who had previously announced support for the GOP frontrunner, attended the meeting at Jones Day law firm near the U.S. Capitol.
"Party unity is critical if we're going to win," said former Rep. Bob Livingston of Louisiana, who joined the meeting. "Once these Republicans who are balking right now stop and reflect about the alternatives, and that we could actually be faced with four years of Hillary Clinton, they're all going to unify. That's a good reason to come in and get behind Donald Trump."
Rep. Scott DesJarlais told MSNBC's Chris Matthews that Trump was "warm" and "engaging" during the in-person meeting and that people within his party and outside of it should "get used the idea that this very well could be our president."
"I definitely left with a great impression of the man," he said.
In a press conference later Monday, Trump called the gathering a "beginning meeting" with "a lot of the most respected people in Washington."
Sen. Jeff Sessions, the candidate's most prominent congressional voice on national security and immigration policy, attended. So did Arkansas Sen. Tom Cotton, Rep. Renee Ellmers of North Carolina, former Sen. Jim DeMint, Rep. Scott DesJarlais of Tennessee and Trump endorsers Rep. Tom Reed of New York and Duncan Hunter of California.
Former Speaker of the House and 2012 presidential candidate Newt Gingrich, who has not yet formally endorsed a presidential candidate, joined the meeting along with his wife, Callista.
Attendees called the discussion "frank" and said it included exchanges about the GOP frontrunner's path to the GOP nod.
"I think he has the clearest path to the nomination and it only makes sense that he unify the party and get the people behind him," said DesJarlais.
But GOP congressional leaders, including top members of the House and Senate leadership teams, were not part of the gathering.
Trump's courtship of D.C. Republicans - which will be coupled Monday with an afternoon address to the high-profile American Israel Public Affairs Committee's annual policy conference - was met with derision from Trump's foes within the party.
Conservative commentator and leading Trump critic Erick Erickson wrote Monday that the Jones Day meeting constitutes a "capitulation of the Republican Establishment" where "leaders of the party will gather to kneel before Donald Trump and pledge allegiance to him."
"Conservatives should take note of who enters and exits 51 Louisiana Avenue today and hold them accountable," he added, referencing the address of the law firm.
In a separate statement, Liz Mair of anti-Trump organization Make America Awesome mocked the "tiny, tiny group" of GOP lawmakers attending the meeting, describing the gathering as a "sell-your-soul session" with few participants.
Trump's schedule on Monday also included a meeting with the editorial board of The Washington Post in the nation's capital.
During that meeting, Trump for the first time named several people who he says have been advising him on foreign affairs, including former Army Lieutenant General Keith Kellogg, former Defense Department inspector general Joe Schmitz and energy expert George Papadopoulos.
NBC's Alex Jaffe contributed to this report.