President Donald Trump and Republican Senate leaders are engaged in a frantic search for votes in a last-ditch effort to repeal and replace the Obama health law. The outcome is uncertain in a Capitol newly engulfed in drama over health care.

Senate Majority Leader Mitch McConnell, whose failure to pass a repeal bill in July opened a bitter public rift with Trump, is pressing hard for the newly revived effort, which had been left for dead as recently as a week or two ago. But in a sign he remained short of votes, McConnell refused on Tuesday to commit to bringing the legislation up for a vote.

Republicans must act by Sept. 30 in the Senate or face the prospect of a Democratic filibuster.

That blocking action is currently staved off by budget rules that will expire at the end of the month. The new legislation, by Graham and Sen. Bill Cassady, R-La., would undo the central pillars of former President Barack Obama’s law and replace them with block grants to the states so they could make their own health care coverage rules.

“I hope Republican Senators will vote for Graham-Cassidy and fulfill their promise to Repeal & Replace ObamaCare. Money direct to States!” Trump said in a tweet Wednesday.

McConnell, in remarks on the Senate floor, had said: “Governors and state legislators of both parties would have both the opportunity and the responsibility to help make quality and affordable health care available to their citizens in a way that works for their own particular states.” He called it “an intriguing idea and one that has a great deal of support.”

Democrats are unanimously opposed, arguing that the legislation would result in millions of Americans losing their health insurance, decreased access to affordable care and a damaged Medicaid health program for the poor.

McConnell must win the votes of 50 of the 52 Senate Republicans. That would amount to victory in the 100-member Senate, because GOP Vice President Mike Pence would then break a tie.

Pence appeared at the Capitol on Tuesday and declared the Trump administration was “all-in” on the effort. The president himself was closely in touch with Graham and others.

If the bill does pass, Speaker Paul Ryan, R-Wis., has committed to pushing it through the House as-is, and straight to the president’s desk, according to Graham.

After seven years of promises to get rid of Obama’s law, Republicans would have finally succeeded. It would be a promise kept to the GOP base, yet one with uncertain and potentially devastating political consequences for the Republican Party given that millions of people would be likely to lose their health coverage and others might have skimpier care.