“We promised the American voters that we would repeal Obamacare,” Mr. Paul said. “But when you’re keeping half the taxes, most of the regulations and creating a brand-new insurance bailout superfund, that to most people just doesn’t look like repeal.”
Ms. Collins has been a vocal critic of the bill for very different reasons.
“If the Medicaid cuts remain the same in the new version of the Senate bill, I will vote no on the motion to proceed,” she said Wednesday, referring to the first step required to begin debate.
As Senate Republicans struggled for agreement on the contents of their repeal bill, President Trump exerted pressure. “I am sitting in the Oval Office with a pen in hand, waiting for our senators to give it to me,” he said in an interview with Pat Robertson, the founder of the Christian Broadcasting Network.
Mr. Trump offered a warning about what would happen if the Senate failed.
“Well, I don’t even want to talk about it because I think it would be very bad,” Mr. Trump said. “I will be very angry about it, and a lot of people will be very upset.”
Republicans hold 52 seats in the Senate and can afford to lose only two of their members on votes to take up and pass the legislation, which is opposed by all the Democrats. Vice President Mike Pence would cast the tiebreaking vote if there is a 50-50 split.
“We just have differences that are legitimate about how the health care legislation affects our states,” said Senator Rob Portman, Republican of Ohio, who said before the Fourth of July recess that he did not support the repeal bill as it had been written. “Some people feel strongly one way, and others another way. But we’re trying to find middle ground.”
Mr. McConnell has been considering changes in his bill that would increase insurance subsidies for low-income people and preserve two taxes imposed on high-income people by the Affordable Care Act. The bill is still expected to make huge changes in Medicaid, putting caps on federal payments to states and rolling back the expansion of the program under the Affordable Care Act that has extended insurance to millions of people.
One issue still up in the air is a proposal by Senator Ted Cruz, Republican of Texas, that would allow insurers to sell less comprehensive plans if they also offered at least one option that complied with federal standards. The stripped-down plans could omit certain types of coverage, such as maternity or mental health care.
Groups representing patients and insurers flooded Senate offices Wednesday with correspondence opposing the proposal. “The Cruz proposal would result in higher, not lower, premiums for people with serious and chronic conditions,” said a letter from 13 patient advocacy groups including the American Heart Association and the lobbying arm of the American Cancer Society.
Scott P. Serota, the president and chief executive of the Blue Cross Blue Shield Association, said the Cruz plan “would create two sets of rules for health insurance products” and could make coverage unaffordable for people with pre-existing conditions.
Senator Mike Rounds, Republican of South Dakota, suggested some kind of regulation to limit the difference in prices for compliant and noncompliant insurance plans, so premiums would not be “outrageously high” for people with pre-existing conditions.
But that was dismissed by Mr. Paul as a form of price controls.
And Mr. Cruz pushed back against insurers’ criticism.
“Insurance companies have made billions of dollars under Obamacare,” Mr. Cruz said, “and their focus appears to be on maximizing their own subsidies at the expense of consumer choice.”
Democrats may not have the votes to stop the Republican push to repeal the Affordable Care Act, but they do have Senate rules to help them. Under the procedure that Republicans are using to speed passage of the health care bill, senators can object to a provision if it does not change federal spending or revenue or if the budgetary effects are “merely incidental” to some policy objective.
Republicans and Democrats are making formal presentations this week to the Senate parliamentarian, Elizabeth MacDonough, who serves as a sort of referee, deciding whether specific provisions of the bill comply.
Democrats are preparing to challenge these provisions, among others:
• Planned Parenthood. The bill would cut off federal Medicaid funds for Planned Parenthood for one year. The Congressional Budget Office said this would reduce federal spending by $225 million, of which more than one-third would be offset by higher costs for additional births to women covered by Medicaid. Democrats say the policy goal outweighs the budgetary impact.
• Age ratios. The bill would let insurers charge older consumers five times as much as young adults. Under the Affordable Care Act, they can charge no more than three times as much. Democrats say the purpose of the change is regulatory, not budgetary.
• Waiting period. People who went without insurance for approximately two months or more in the prior year would be required to wait six months before they could start coverage under the Senate bill. Democrats say the purpose is not to save money, but to regulate insurance and to encourage people to obtain coverage without mandating it.
• Abortion coverage. The bill would prevent consumers from using federal tax credits to help pay premiums for insurance that includes coverage of abortion. Republicans say this could save money. Democrats say that the Republican goal is to regulate insurance and to reduce abortions, and that the proposal would not affect federal spending.