The 142-page draft repeals most of Obama's health care reforms. The Senate plan phases out the expansion of Medicaid and repeals taxes on the wealthy and insurance companies.
US Senate Republicans on Thursday unveiled their version of legislation that would replace Obamacare, proposing to kill a tax on the wealthy that pays for it and reduce aid to the poor to cut costs.
With Democrats deeply opposed to Republican attempts to overhaul former President Barack Obama's signature healthcare law, the route to passage was extremely narrow for Republicans, who control both houses of Congress.
There were no assurances that moderates and conservatives will be able to bridge their differences.
The proposal, worked out by Senate Majority Leader Mitch McConnell with other Republican leaders in secret, was welcomed by President Donald Trump.
TRT World's Azadeh Ansari reports from Washington DC.
The president privately bashed as "mean" a version passed last month in the House of Representatives, according to congressional sources.
Trump, who said on Wednesday that he wants a health plan "with heart," told reporters at the White House that healthcare legislation will require "a little negotiation, but it's going to be very good." He said he doubted Democrats would help.
The draft bill proposes repealing the 3.8 percent net investment income tax on high earners retroactively to the start of 2017, not at some point in the future, as some analysts had speculated.
The tax, which affects high-income Americans and was imposed to help pay for Obamacare, has been a key target for Republicans.
The Senate bill maintains much of the structure of the House bill, but differs in several key ways.
It would phase out Obamacare's expansion of the Medicaid program for the poor and disabled over three years, from 2021 to 2024, and then enact deeper cuts in the program than the House version beginning in 2025.
It would also allow states to add work requirements for some Medicaid enrollees.
The legislation also reshapes subsidies to low-income people for private insurance.
TRT World's Ediz Tiyansan reports from Washington DC.
Democratic leaders of Congress, who want the Obamacare law fixed but not abandoned, immediately assailed the Senate Republican version.
"The president said the House bill was mean," said Senate Democratic leader Chuck Schumer. "The Senate bill may be even meaner."
Like the House bill, the Senate would repeal a penalty associated with the individual mandate to have health insurance or else pay a fine.
Policy experts said that would keep more young, healthy people out of the market and likely create a sicker patient pool.
The legislation would also repeal the penalty associated with the employer mandate that they provide employees health insurance.
The Senate bill would provide money to stabilise the individual insurance market, allotting $15 billion per year in 2018 and 2019 and $10 billion per year in 2020 and 2021.
The nonpartisan Congressional Budget Office (CBO) has estimated that the House bill would kick 23 million people off their healthcare plans. The CBO is expected to weigh in on the Senate draft bill early next week.
As lawmakers made speeches about the legislation on the Senate floor, a protest erupted outside McConnell's personal office, with many people in wheelchairs blocking a hallway, holding signs and chanting. Capitol police were on the scene and physically removing protesters.