(Adds announced committee hearings; updates share prices)
By Susan Cornwell
WASHINGTON, Sept 18 (Reuters) - Democratic leaders in the U.S. Congress on Monday demanded that lawmakers wait to find out the budgetary and healthcare impacts of a new, last-ditch legislative effort by Republicans to repeal Obamacare before voting on it.
In their long-running war on former President Barack Obama's signature healthcare law, Senate Republicans are now proposing to replace it with a system that would give states money in block grants to run their own healthcare programs.
Drafted by Republican Senators Lindsey Graham and Bill Cassidy, the bill was introduced last week. Graham and Cassidy said they were close to securing the votes needed for passage, but the bill's outlook was uncertain.
If approved, it would replace the 2010 Affordable Care Act, known informally as Obamacare, which Republicans have long seen as government overreach into the healthcare business.
The Graham-Cassidy measure has revived a fight that many in Washington thought was over when an Obamacare repeal-and-replace bill flopped in the Senate in July, humiliating Republican Senate Majority Leader Mitch McConnell and President Donald Trump.
Two Senate committees, including the powerful Finance Committee, on Monday announced they would hold hearings on the bill next week, the first public hearings all year for any Republican Senate proposal to overhaul Obamacare.
Republican Senator John McCain had called for a return to regular order and public hearings before voting against a repeal-and-replace bill in July. Senator Ron Wyden, the top-ranking Democrat on the Finance Committee hearing, said next week's hearing "makes a mockery of regular order."
The Congressional Budget Office, a non-partisan fiscal analysis unit of Congress, said on Monday it will make a preliminary assessment of the bill's impact next week. But it said it will not be able to estimate the impact on the deficit or changes in insurance coverage or premiums for several weeks.
Worried Democrats seized on the statement to urge Republicans to wait for a full CBO score before holding a vote.
"Have the courage and decency to wait for a CBO score," Senate Democratic leader Chuck Schumer said on the Senate floor on Monday.
The House of Representatives is on a break this week.
A delay to wait for a CBO analysis is something Republicans can ill afford since in two weeks Senate procedural rules will make it much more difficult for them to advance the legislation.
A special parliamentary procedure that would allow the bill to move forward in the Senate with a simple majority of only 51 votes will expire in two weeks. After that, it would need 60 votes, like most Senate legislation. Republicans have a slim 52-vote Senate majority.
Schumer called Graham-Cassidy a "Frankenstein monster of a bill" that would be costly for some states. He said Democrats would use every procedural tool to slow or stop its passage.
Stock prices fell for small hospital chains that have high corporate debt loads and that likely would be hurt under the plan’s probable decrease in government payments for patients.
Community Health Systems closed down 35 cents, or 4.6 percent, to $7.26, and Tenet Healthcare fell $1.01, or 6.0 percent, at $15.72.
Trump has been telephoning members of Congress in recent days urging action on dismantling Obamacare.
McConnell has not promised to bring Graham-Cassidy to the floor for a vote, but he asked the CBO for a quick assessment.
Not all the Senate's conservatives back the bill.
Senator Rand Paul said it did not go far enough to repeal Obamacare. Senator John Kennedy of Louisiana told reporters he was worried that the bill would allow some states to set up their own single-payer healthcare system.
McCain and two other Republican senators, Lisa Murkowski and Susan Collins, all of whom voted against the last Republican effort to repeal Obamacare, were said by aides to be undecided on the latest proposal.
Collins, of Maine, told reporters she was still analyzing the measure, but listed several concerns, including possibly higher insurance premiums for older Americans. She said the Maine Hospital Association calculated her state would receive a billion dollars less in Medicaid and other federal healthcare spending over the next decade under the bill, and "that obviously is of great concern to me."
But if it can get through the Senate, the plan may have a chance in the House of Representatives, also controlled by Republicans.
Past Republican proposals to dismantle Obamacare have been hampered, in part, by CBO estimates that showed the bills would have left millions more Americans without health insurance.
Obama's healthcare reform has provided health benefits to 20 million Americans. (Additional reporting by Makini Brice, Roberta Rampton, Caroline Humer and Richard Cowan; Editing by Cynthia Osterman and Leslie Adler)