House Republicans and President Donald Trump celebrated on Thursday (4 May) after a healthcare bill intended to repeal and replace Obamacare narrowly passed earlier in the day. However, the celebrations may be short-lived as the contentious bill faces an uphill battle in the Senate.

The bill is expected to undergo major changes, with some Senate Republicans saying they will not vote on the House-passed bill but will write their own legislation. The Washington Examiner says a Senate proposal is being developed by a 12-person group that will attempt to incorporate some elements of the original bill but will not use it as a basis.

"The safest thing to say is there will be a Senate bill, but it will look at what the House has done and see how much of that we can incorporate in a product that works for us in reconciliation," Senator Roy Blunt (R-Mo.) said.

The proposed plan was confirmed by Senator Chuck Grassley (R-Iowa) and Senate Majority Whip John Cornyn (R-Texas). Cornyn told the Examiner that the group has been meeting for weeks.

"What we have to do is build a consensus among our conference and that is what the working group is designed to do," he said. "To get to a compromise we can agree to and then present it to the larger conference."

Cornyn added that the group does not have a deadline to produce a bill and that they are instead focused on reaching 51 votes - the threshold for it to pass in the 100-seat Congress.

Slim margins for GOP

The New York Times says the GOP's slim 52-member majority in the Senate gives them little room for defectors. A number of Republican senators have expressed their concerns over the House bill, including insurance costs for poorer, older Americans and cuts to Medicare.

Other senators are simply unsure what the House actually voted on. "Don't know what's in it," Senator Lindsey Graham (R-SC) said before the vote. "Waiting to see if it's a boy or a girl." Graham conceded that it seemed as though the House was moving towards more state control over the healthcare system, yet remained wary.

"But any bill that has been posted less than 24 hours - going to be debated three or four hours, not scored - needs to be viewed with suspicion," he said. Graham noted that the House vote also came without a new assessment from the Congressional Budget Office on the bill's price and impact, the Times reports.

Cornyn noted that Senator Susan Collins (R-Maine), who has co-authored an Obamacare replacement bill with Senator Bill Cassidy (R-La.), "has been an integral part of the discussions". The bill written by Collins and Cassidy would allow states to decide to keep Obamacare or provide an alternative that would auto-enroll residents in a basic health insurance and pharmacy plan, reports the Examiner.

Senate Republicans will also have to decide whether they will use a procedural tool known as reconciliation to pass the bill with a simple majority. Otherwise they will be forced to clear the 60-vote threshold with the support of Democrats.

If the 60 votes are needed, Democrats will likely provide little help, if Senator Chris Murphy (D-Conn.) is anything to go by. "I hope this thing is dead on arrival, and I hope a ton of House members lose their seats for voting for something this inhumane," he said.