WASHINGTON - US House Republicans are working on changes to their healthcare overhaul bill to provide more generous tax credits for older Americans and add a work requirement for the Medicaid program for the poor, House Speaker Paul Ryan said on Sunday.

Ryan said Republican leaders still planned to bring the healthcare bill to a vote on the House of Representatives floor on Thursday. Speaking on the "Fox News Sunday" television program, he said leaders were working to address concerns that had been raised by rank-and-file Republicans to the legislation.

Republicans remain deeply divided over the healthcare overhaul, which is President Donald Trump's first major legislative initiative. It aims to fulfill his campaign pledge to repeal and replace the Affordable Care Act, popularly known as Obamacare, the signature healthcare program of his Democratic predecessor, Barack Obama.

Democrats say the Republican plan could throw millions off health insurance and hurt the elderly, poor and working families while giving tax cuts to the rich.

"We think we should be offering even more assistance than the bill currently does" for lower-income people age 50 to 64, Ryan, the top Republican in Congress, said of the tax credits for health insurance that are proposed in the legislation.

Ryan also said Republicans were working on changes that would allow federal block grants to states for Medicaid and permit states to impose a work requirement for able-bodied Medicaid recipients.

Trump told reporters in a brief conversation aboard Air Force One that he had meetings about healthcare reform in Florida at the weekend and that the effort to sell the proposal was going well.

He has been wooing lawmakers to vote for the bill and won the backing of a dozen conservative lawmakers on Friday after an Oval Office meeting in which the president endorsed a work requirement and block-grant option for Medicaid.

Trump is set to meet Ezekiel Emanuel, a health policy special adviser under Obama who helped shape the Affordable Care Acton, at the White House on Monday, along with Ryan and Health and Human Services Secretary Tom Price.

Block grants would give states a set amount of money to cover people on the Medicaid program and provide flexibility in spending decisions. However, there is no guarantee funding would keep up with future demands.