Republicans took major political risks by backing a deeply controversial bill, and Democrats hope to make them pay at the polls in midterm elections next year.
Wrangling now shifts to the Senate, where Republicans, who hold a slim majority there, say they are readying their own health care measure. The end result could look quite different from what narrowly cleared the House of Representatives Thursday.
Democrats seized the offensive, insisting it was a pipe dream to think the Republican plan forecast to push 24 million people off insurance could become law as it stands.
"This Republican health care bill needs to either be flushed down the toilet or thrown in the garbage. It's not getting through the Senate," Senator Bernie Sanders fumed on Twitter.
"Trumpcare battle is just beginning," added House Democrat Joe Kennedy III, urging liberal senators like Elizabeth Warren to lead the upcoming fight.
Moderate Senate Republicans are expected to reject or tweak several elements of the bill. Several have expressed concern about the House plan's rollback of Medicaid, limited assistance for low-income Americans, and a provision that allows insurers to increase premiums for people with pre-existing conditions -- a practice the current law prohibits.
The White House insisted Friday that negotiators are focused on "big principles" such as lowering costs and empowering states, and that tweaks were inevitable.
"I feel like there will be some changes, that is part of the process," White House spokeswoman Sarah Huckabee Sanders said.
Trump raised eyebrows after the House win when he praised Australia's government-funded health care system during a meeting with Prime Minister Malcolm Turnbull.
But Trump backpedaled Friday, tweeting: "Of course the Australians have better healthcare than we do -- everybody does." But with the replacement of Obamacare, he added, "our healthcare will soon be great."
It was Trump himself who proclaimed in January that repealing and replacing the Affordable Care Act will lead to "insurance for everybody."
But the House bill falls short of that goal, and Democrats have warned that it exposes millions of vulnerable Americans.
House Republican Conference chairwoman Cathy McMorris Rodgers highlighted her son's Down syndrome to show that the Republican goal of protecting people with pre-existing conditions was "a personal mission" for her.
"Despite what people are saying, House Republicans aren't seeking to strip these protections — or anyone's protections — away," she wrote in the Washington Post.
Democrats have taunted Republicans about possibly losing their House majority in 2018 because of their votes.
The Cook Political Report shifted its ratings for 20 Republican districts in the 2018 elections to reflect improved Democratic chances. Most ratings went from "likely Republican" to "lean Republican" or from "lean Republican" to "toss up."
