By Richard Cowan and Yasmeen Abutaleb
WASHINGTON, May 4 (Reuters) - The U.S. House of Representatives was set on Thursday for a cliffhanger vote to repeal Obamacare, as Republican leaders worked to deliver President Donald Trump a win for one of his top legislative priorities.
House Republican leaders have expressed confidence the bill would pass and several party moderates who previously objected to it got behind it on Wednesday, giving the effort new momentum.
Still, the vote was expected to be close. Even if the measure passes the House, it faces daunting odds in the Senate where Republicans hold a narrower majority.
Keen to score his first major legislative win since taking office in January, Trump threw his own political capital behind the bill, meeting lawmakers and calling them in an effort to cajole their support.
Trump, whose Republican party controls both the House and Senate, is seeking to make good on his campaign promise to repeal and replace Obamacare.
Aides said he worked the phones furiously.
Wavering moderate Republicans had worried that the legislation to overhaul President Barack Obama's 2010 signature healthcare law would leave too many people with pre-existing medical conditions unable to afford health coverage.
But the skeptical Republican lawmakers got behind the bill after meeting with Trump to float a compromise proposal that is still expected to face unanimous Democratic opposition.
The legislation's prospects brightened further after members of the Freedom Caucus, a faction of conservative lawmakers in the House who played a key role in derailing the original version of the bill last month, said they could go along with the compromise.
Millions more Americans got healthcare coverage under Obamacare, but Republicans have long attacked it, seeing it as government overreach and complaining it drives up costs.
Called the American Health Care Act, the Republican bill would repeal most Obamacare taxes, including a penalty for not buying health insurance. It would slash funding for Medicaid, the program that provides insurance for the poor, and roll back much of Medicaid's expansion.
The latest effort comes after earlier pushes by Trump for healthcare reform collapsed twice, underscoring the difficulty of uniting the various factions of the Republican party.
Earlier this week, prospects for the legislation appeared grim as several influential moderate Republicans said they could not support the bill citing their concerns about people with pre-existing conditions.
Putting a spotlight on the concerns about pre-existing conditions, late-night talk show host Jimmy Kimmel made a tearful plea for retaining that provision in Obamacare as he recounted a medical emergency that arose with his newborn son.
Kimmel's monologue about his son's congenital heart condition went viral on social media.
House Democrats have rejected the latest change to the Republican legislation on Wednesday, saying it did not go far enough toward protecting people with pre-existing conditions.
"Republicans have made Trumpcare even more dangerous and destructive than the last time they brought it to the floor," Democratic Leader Nancy Pelosi wrote to her caucus in a letter late Wednesday night.
Democrats have long thought their best chance of stopping the repeal would be in the Senate, where only a few Republicans would need to defect to stop the law from moving forward.
The difficulty in the House is now making Democrats optimistic that Republicans will face backlash from voters and face losing seats in the 2018 midterm elections. (Additional reporting by David Morgan, Steve Holland, Roberta Rampton and Eric Beech; Writing by Ginger Gibson; Editing by Caren Bohan and Robert Birsel)