Is everyone covered, or will 24 million people be losing health care coverage, as has been feared?
President Donald Trump is urging Senate Republicans to "not let the American people down".
White House Budget Director Mick Mulvaney, speaking on CBS' "Face the Nation" on Sunday morning, said, "The bill that passed out of the House is most likely not going to be the bill that is put in front of the president".
"Republican Senators will not let the American people down!"
Major medical and other groups, including the American Medical Association, opposed the House bill. Under Obamacare, health insurance premiums spiked.
No analysis was done by the nonpartisan Congressional Budget Office before the vote so that lawmakers - and the public - would know its effects on US health care.
Senate Majority Leader Mitch McConnell, R-Ky., plans to move forward under special procedures that allow legislation to pass with a simple majority vote, instead of the 60 usually required for major bills in the Senate.
Ryan, for instance, offered a spirited defense of the House bill on ABC's "This Week" as he was peppered with questions about the possibility of sharp premium increases for people with preexisting conditions and the worry that many people on Medicaid will lose their coverage. Chief among them: a guarantee of paying the same amount for coverage regardless of health history.
A political group with ties to House Republican leadership, American Action Network, said Sunday it was buying $500,000 in television time to promote the Republican health care bill.
House Republicans finally pushed through a bill to gut Barack Obama's Affordable Care Act. For now, one doesn't have to be a fan of the Affordable Care Act or a Democrat to conclude that what happened Thursday did not represent progress toward a better America.
Among those being targeted are Tom MacArthur of New Jersey, the moderate Republican who helped revive the bill by authoring an amendment on pre-existing conditions, as well as Dave Brat of Virginia, a conservative Freedom Caucus member.
"Sometimes in life you have to do what's right, not what's politically expedient, " Priebus said during an appearance on "Fox News Sunday".
Collins, along with fellow Republican Senators Rob Portman, of OH, and Lindsey Graham, of SC, have in recent days spoken out forcefully against parts of the House bill, with Graham saying it "needs to be viewed with suspicion" and Portman asserting that "it does not meet the test of stability" for people who rely on the "safety net" of Medicaid.