* Senate Finance Committee to hold hearing Monday
* Republican moderate worries about impact on Medicaid (Adds Paul still opposes bill, share prices, Graham quote)
WASHINGTON, Sept 25 (Reuters) - Republican senators tried to gather more support on Monday for a last-ditch attempt to repeal Obamacare by revising funding provisions of their bill to make it more attractive to a handful of undecided lawmakers.
The outcome remained in doubt, with several senators in the party voicing concerns in recent days about the legislation to dismantle Democratic former President Barack Obama's signature healthcare law.
Republican senators leading the effort on Monday released a revised version of their bill in hopes of finding more support.
The Senate is up against a Saturday deadline for deciding the fate of the 2010 Affordable Care Act, as it is known formally. That is the day for expiration of a rule that would let the latest Republican plan pass with just a 51-vote majority, instead of the more usual 60 votes. Republicans, who control the Senate 52-48, were finding it difficult even to clear that lower hurdle.
A total of three Republican defections would kill off the latest anti-Obamacare effort and Republican Senators John McCain and Rand Paul already have registered their opposition. Others senators such as Ted Cruz, Susan Collins and Lisa Murkowski have voiced reservations.
A spokesman for Paul said on Monday the senator still opposes the latest version despite the tweaks.
The revised bill released on Monday included a table that said some states where senators have been undecided, such as Alaska and Maine, would get more money under the bill than under current law. The Washington Post first reported the revision.
For seven years, Republicans have hammered Obamacare, which extended health insurance to some 20 million Americans, as an unwarranted and costly government intrusion into healthcare, while also opposing taxes it imposed on the wealthy.
Republican President Donald Trump made repealing Obamacare one of his top campaign promises in 2016. Democrats have fiercely defended it.
Democratic leaders roundly rejected the revised draft of the repeal legislation as a sleight of hand to gain support.
The last attempt to repeal Obamacare fell one vote short in July, in a humiliating setback for Trump and Senate Majority Leader Mitch McConnell.
The new bill, originally introduced by Senators Lindsey Graham and Bill Cassidy, would take federal money spent on the Medicaid program for the poor and disabled, as well as subsidies to help Americans buy private insurance, and divvy it up to the states in block grants. Advocates say that would give states more discretion to manage their own healthcare schemes.
Opponents fear undoing Obamacare will mean millions lose healthcare, including some with pre-existing medical conditions.
U.S. hospital stocks were down across the board, in broadly bearish trading marketwide. Shares of HCA Healthcare Inc and Tenet Healthcare Corp were hit particularly hard, falling 2.8 percent and 5 percent, respectively, in afternoon trading.
"The Graham-Cassidy bill is looking to reduce funding for Medicaid in the longer term," said Jefferies analyst Brian Tanquilut. "That is a benefit that we have seen improve the earnings outlooks for these hospitals."
He said the bill could reduce the number of insured Americans, which would hurt hospitals' bottom lines.
PAUL WANTS 'SIGNIFICANT REASSESSMENT'
Paul, from Kentucky, said the Graham-Cassidy plan was still too similar to Obamacare. "My promise to the voters was to repeal Obamacare - not block grants and keep Obamacare," Paul said in a statement. Only a "significant reassessment" of the "trillion-dollar spending regime" would get his support, he said.
Cruz, a conservative speaking at an event in his home state of Texas, warned on Sunday that Trump and McConnell could not count on his vote. Cruz has pushed for greater government cost savings in healthcare.
Collins, a moderate from Maine who voted against her party's bill in July, said on CNN's "State of the Union" on Sunday that it was difficult to "envision a scenario where I would end up voting for this bill." She worried about cuts to Medicaid benefits to the poor and disabled.
Graham suggested Republicans could have another shot at repealing Obamacare, even if they do not do it this week, if Senate leadership were to attach a repeal bill to a planned tax reform package.
That package was expected to be designated in 2018 for the once-per-year procedural advantage of being handled under the Senate's 50-vote reconciliation process. Trying to combine the two would be highly unusual.
"If we fall short, then you just continue the effort in putting taxes and reconciliation together," Graham told Reuters. "I think Congress can do two things at once."
U.S. Senate Democratic leader Chuck Schumer dismissed the late effort to revise the bill and add money for a few states, calling it "just as bad for those states and the rest of the states because it still contains a massive cut to Medicaid."
The Senate Finance Committee is scheduled to hold a hearing on Monday in an attempt to build support for the bill and to tamp down Democratic criticism that the measure has not been thoroughly vetted.
The non-partisan Congressional Budget Office is expected to produce as early as Monday a preliminary analysis of the bill that would assess its impact on budget deficits.
More time is likely needed for the CBO to gauge how the bill could affect Americans' access to health insurance. (Reporting by Susan Cornwell and Richard Cowan; Additional reporting by Phil Stewart and Alistair Bell; Editing by Mary Milliken and Bill Trott)