WASHINGTON — Hoping to revive their bill to repeal the Affordable Care Act, Senate Republicans said Thursday they were seriously considering proposals to keep one of the law’s taxes on high-income people while providing more money to combat the opioid epidemic.

In addition, Republicans said, they are considering a proposal that would allow insurers to sell cheaper, less comprehensive health plans if they also offered at least one plan that complies with consumer protection standards like those in the Affordable Care Act.

The open talk of leaving in place a tax on investment income was a big break from the House-passed health care bill and from the Senate’s initial approach. And it was championed by reliably conservative Republicans who acknowledged the tough choices that the health bill would force on lower-income Americans.

“It’s not equitable to have a situation where you’re increasing the burden on lower-income citizens and lessening the burden on wealthy citizens,’’ said Senator Bob Corker, Republican of Tennessee. “That’s not a proposition that is sustainable, and I think leadership knows that.’’

But the negotiations themselves are attracting controversy, and personal strains are showing. The Senate majority leader, Mitch McConnell of Kentucky, dressed down Senator Rob Portman, Republican of Ohio, this week over Medicaid cuts. Senate Republicans bristled after a super PAC tied to President Trump went after one of their own for opposing the bill, Dean Heller of Nevada. Adding to the insult, one of the top officials of that group, Nick Ayers, was named chief of staff of Vice President Mike Pence’s office — after the blowup.

McConnell was briefing senators Thursday about possible changes in the repeal bill, hoping for broad agreement by the end of the week so he can submit it to the Congressional Budget Office for an official assessment. He scrapped plans for a vote on the bill this week after he met broad resistance from Republican senators across the ideological spectrum.

McConnell’s efforts were complicated by a separate CBO report released Thursday that projected Medicaid spending under the Senate would be 35 percent lower after two decades. The new report detailed how Medicaid changes would cut more deeply as they go fully into force.

By the end of Thursday, McConnell’s caucus still appeared far from a consensus, and it was unclear when a new version of the bill would be ready.

The nonpartisan budget office had already said that the bill would cut projected Medicaid spending 26 percent by 2026. “A large gap would grow between Medicaid spending under current law and under this bill,’’ the new report said, and that gap would widen, so that federal Medicaid spending in 2036 would be more than a third lower under the bill than under the Affordable Care Act.

“That is going to cause a lot of harm, and that’s one of my biggest concerns about the bill,’’ Senator Susan Collins of Maine, a crucial Republican holdout on the bill, told CNN after the release.

This week, for the first time, Republicans are talking publicly about keeping a tax on capital gains and other investment income, imposed by the Affordable Care Act on individuals with annual incomes exceeding $200,000 and couples making more than $250,000.

McConnell’s bill would repeal that tax, like most other taxes in Obama’s health care law. The CBO said that repealing the investment tax, retroactive to the start of this year, would cost the government $172 billion in lost revenue from 2017 to 2026.

Corker and Senator John Cornyn of Texas, the No. 2 Republican, said party members were discussing the idea of keeping the investment tax.

Conservative Senator Mike Lee of Utah took a swipe at “tax cuts for the affluent’’ in listing his concerns with the bill.

Collins said, “I do not see a justification for doing away with the 3.8 percent tax’’ on certain investment income. Collins said the investment tax differed from other taxes in the Affordable Care Act, like an excise tax on medical devices, because those taxes can increase costs for health care consumers.

“I distinguish between those tax increases that were part of Obamacare that increase premiums and the cost of health care versus those that don’t,’’ Collins said.

The Congressional Budget Office has said McConnell’s bill could increase costs for low-income people to the point that “few low-income people would purchase any plan,’’ even with financial assistance available from the government.

Senate Republicans also said they were considering adding billions of dollars to the repeal bill to help pay for the prevention and treatment of opioid abuse. This provision is meant to woo wavering Republicans from states hard hit by the opioid epidemic, including Portman and Shelley Moore Capito of West Virginia.

It is not clear whether the additional funds would match the amount sought earlier by Portman and Capito: $45 billion over 10 years.

The CBO said that over 10 years, McConnell’s bill would cut more than $770 billion from projected spending under Medicaid, a program that pays for a large share of substance abuse treatment and prevention costs in many states.