WASHINGTON (AP) — Showdown day at hand, Republicans remained short of votes Thursday for their health care overhaul and were hoping President Donald Trump would close the deal with a bloc of conservatives at a White House meeting that could determine the fate of their showpiece legislation.

Frenzied last-minute wheeling and dealing was under way on Capitol Hill and in the White House, where Trump summoned the balky conservative House Freedom Caucus to meet with him mid-day, ahead of the planned vote. But concessions being offered to the conservatives, who sought to limit requirements for health plans to offer certain benefits including substance abuse and maternity care, appeared to be scaring off moderate Republicans.

“An agreement is needed from my party,” Rep. Pete Sessions, R-Texas, said Thursday during a procedural debate on the House floor. He said the GOP “intends to bring forth an agreed-to bill that we will be able to show to the American people, and we will own it.”

In one signal that more work was needed, GOP leaders postponed a planned morning meeting of House GOP lawmakers as all eyes turned toward Trump and the conservative caucus. Most of the Republican rebels were from that group.

The stakes could hardly be higher for a party that gained monopoly control of Washington largely on promises to get rid of former President Barack Obama’s signature legislative achievement and replace it with something better. Now Republicans are staring at the possibility of failure at the very moment of truth, an outcome that would be a crushing political defeat for Trump and Hill GOP leaders and would throw prospects for other legislative achievements into extreme uncertainty.

The Republican legislation would halt Obama’s tax penalties against people who don’t buy coverage and cut the federal-state Medicaid program for low earners, which the Obama statute had expanded. It would provide tax credits to help people pay medical bills, though generally skimpier than the aid Obama’s statute provides. It also would allow insurers to charge older Americans more and repeal tax boosts the law imposed on high-income people and health industry companies.