Republicans' last-ditch effort on Obamacare repeal is gaining some steam - but it still faces key hurdles

Senate Republicans' last-ditch effort to repeal and replace the Affordable Care Act is gaining steam, but several complications could prove to be insurmountable hurdles for the GOP's latest gambit.

The bill proposed and named after Sens. Lindsey Graham, Bill Cassidy, Dean Heller, and Ron Johnson would send most federal funding for healthcare programs like Medicaid to individual states in the form of a lump sum.

Republicans are facing an end-of-September deadline to pass healthcare-related legislation through the process of reconciliation, which allows them to move measures by a simple majority vote. Recent developments have increased chances that Republicans could be closer to 50 votes.

Cassidy told reporters Friday that the bill is supported by 48 or 49 GOP members, putting it right on the threshold. Sen. John McCain, one of the holdouts on the previous failed Republican repeal effort, said he would consider voting for the bill.

Separately, Senate Majority Leader Mitch McConnell instructed the Congressional Budget Office to speed up its scoring of the legislation, a move that indicates he is putting some weight behind the effort.

The frenzy to pass the legislation comes as Republicans face an end-of-month deadline to use 2017 budget reconciliation rules. The process allows a bill to pass the Senate with a simple majority vote, bypassing a filibuster, if it brings down the deficit. The Senate parliamentarian, an official of sorts for the chamber's rules, said the current budget reconciliation rules attached to the fiscal year 2017 budget will expire at the end of the month.

Aside from the tight calendar, proponents of the legislation are facing some friendly opposition. Republican Sen. Rand Paul of Kentucky said Friday that he would not vote for the bill.

"I can't support a bill that keeps 90% of Obamacare in place. #GrahamCassidy is not repeal or replace, it is more Obamacare Lite," Paul tweeted.

And the bill contains many of the same Medicaid funding issues that led moderate Republican Sens. Susan Collins and Lisa Murkowski to reject Obamacare repeal and replace bills in July. Republican leaders could only afford to lose two votes to pass legislation with a majority.