Democrats and interest groups vehemently condemned the Republican proposal to replace parts of Obamacare, after the bill passed the House on Thursday.
Earlier, the GOP-sponsored bill passed the House by a vote of 217 to 213. All 193 Democrats voted against the bill. They were joined by 20 Republicans who voted "no."
Liberal firebrands Sens. Elizabeth Warren and Bernie Sanders lambasted the proposal, saying it was a health-care bill in name only.
Warren said the amended proposal is even worse than the original bill and will "devastate Americans' healthcare."
Sanders said the bill "has nothing to do with health care and everything to do with tax breaks for the wealthy." The senator from Vermont called on Americans to rally against the bill and prevent it from passing the upper chamber of Congress.
House Minority Leader Nancy Pelosi said that the GOP now has to live with its choice and that Americans will "have to judge them by how they have acted."
"When you know the facts and you care about people, you can't possibly vote for the bill that they voted for today. So ... either they don't know, they don't care or both," Pelosi said.
An earlier effort to vote on the bill was aborted in late March when GOP leaders saw that it would fail to win enough support to pass it. Before that failed effort, the CBO projected the bill would lead to 24 million more Americans without health insurance over a decade, and insurance plan premium rates up to 20 percent higher than Obamacare rates would be in 2018 before dropping.
The AARP said in a statement that it is "deeply disappointed" in Thursday's outcome, calling the proposal "deeply flawed."
"The bill will put an Age Tax on us as we age, harming millions of American families with health insurance, forcing many to lose coverage or pay thousands of dollars more for health care," the organization said in a statement.
The GOP bill now heads to the Senate, where it stands to face an even larger hurdle as Republicans hold a narrower majority in that chamber.
The American Medical Association called on the Senate to consult all stakeholders to develop a bipartisan solution that would provide "access affordable and meaningful coverage, while preserving the safety net for vulnerable populations."
AMA President Andrew Gurman said the bill in its current form will cause "those with pre-existing health conditions face the possibility of going back to the time when insurers could charge them premiums that made access to coverage out of the question."
The Republican plan "needs important improvements to better protect low- and moderate-income families who rely on Medicaid or buy their own coverage," Marilyn Tavenner, president and CEO of America's Health Insurance Plans, said in a statement.
Civil rights icon John Lewis called the bill's passing "a shame and a disgrace." The Georgia congressman said he has never "seen legislative action that reveals such clear disdain for the human dignity of the most vulnerable among us."
— CNBC's Jacob Pramuk and Dan Mangan contributed to this report.