In recent weeks, Trump has stressed the need for Republicans to come together to repeal the Affordable Care Act, President Barack Obama's sweeping health care law. Trump, angered by the fact no Democrats are working with him on repeal, has slammed the party as "obstructionists," even going so far as to say that he would behave differently if he were a senator.
Since the House passed Obamacare repeal earlier this year, Senate Republicans have been crafting their own repeal bill behind closed doors. Now facing a deadline if they want to finish the legislation this summer, the Trump administration is looking to step up pressure on GOP senators, even if they don't yet have a bill.
Trump's lunch on Tuesday will include a number of more moderate Republicans, including Sen. Rob Portman of Ohio, Sen. Lisa Murkowski of Alaska and Sen. Susan Collins of Maine, and conservatives like Sen. Pat Toomey of Pennsylvania, Sen. Ted Cruz of Texas and Sen. Mike Lee of Utah.
Portman, Cruz, Lee and Toomey are all members of Senate Republican's working group on health care.
Sen. Lamar Alexander, the chair of the Senate Committee on Health, Education, Labor and Pensions, will also attend the lunch, as will Sens. John Thune of South Dakota, John Barrasso of Wyoming, Cory Gardner of Colorado, Tom Cotton of Arkansas, Joni Ernst of Iowa and Orrin Hatch of Utah.
Vice President Mike Pence, who has worked with Senate Republicans for weeks on health care, will also join the lunch.
The President has so-far largely left the Senate to do its work. His legislative affairs team has been closely involved, but the President himself has been removed -- by design, multiple aides say.
Trump will likely accept whatever they come up with -- "Pretty obviously (he's) not a details guy," one Republican aide said -- but will eventually be called on to help rally support for the final product.
Though considerable attention will be focused on the White House lunch, another key meeting will come later on Capitol Hill when Republican senators meet on their own to discuss health care. The meeting, which one Republican aide told CNN was a red-light, green-light, yellow-light situation, is a key moment as Senate leadership attempts to get their conference to coalesce around a baseline health care proposal.
Asked directly on Monday if a bill would be presented to senators on Tuesday, Senate Majority Whip John Cornyn said simply, "No."
Time is of the essence. Senate Majority Leader Mitch McConnell is still targeting a vote before the July 4 recess, even if there are only 14 working days left.
Trump will also meet with "Obamacare victims" on Tuesday when he travels to Wisconsin. Trump met earlier this month with families adversely impacted by growing Obamacare premiums in Ohio.
House Republicans "have done (their) job," Trump said in Ohio, and "now it is the Senate's turn to act and again I hope they are going to act in a very positive manner."