(Monica Akhtar/The Washington Post)

Senate leaders worked Monday to modify their plan to overhaul the Affordable Care Act, adding a provision that would penalize consumers for not keeping their plans, by imposing a six-month waiting provision before they could re-enroll.

The change, intended to satisfy insurers and minimize the number of Americans who may drop their plans if the bill becomes law, received measured praise from some industry officials but sharp criticism from patient advocates.

The move — the first in a series of changes Senate Majority Leader Mitch McConnell (R-Ky.) plans to make in the next few days — underscores the degree to which Republicans need to retool their health bill if they hope to pass it this week.

Some of the targeted measures already in the bill have prompted a backlash, and leaders are navigating between moderate Republicans who want to preserve key aspects of the ACA and conservatives hoping to pare it back even further.

The latest change aims to provide a stronger incentive for younger and healthier Americans to maintain health insurance, by making consumers who drop their policies for 63 days or more face a six-month waiting period before coverage may begin in the following year.

(Peter Stevenson/The Washington Post)

It is one of a number of changes expected in an attempt to appease skittish lawmakers and industry stakeholders as GOP leaders push for a vote on the bill this week.

When Obamacare was negotiated, insurers were wary that they would for the first time be compelled to accept all customers, healthy and sick, without being able to charge people with preexisting medical issues more — or deny them coverage altogether. The industry accepted that new burden on the condition that the law also for the first time require most Americans to have health coverage — meaning that insurers could count on getting healthy new customers as well as those whose medical problems made them more expensive to insure.

Like the conservative health-care bill passed last month by the House, the Senate’s version would end that insurance mandate in 2020. The House’s legislation would replace the mandate with a subtler form of encouragement for people to keep buying insurance — permission for health plans to charge customers 30 percent more for a year if they have let their coverage lapse.

The Senate version lacks such a deterrent, and that prospect has unnerved the insurance industry, whose leaders worry that consumers will postpone buying coverage until they get sick and need care. That sort of behavior would drive up costs and prices.

The Blue Cross Blue Shield Association said in a statement Monday that it was “encouraged” that the Senate proposal “includes several urgently needed and important steps to help make the individual market for insurance more stable and affordable” for the next two years, including the new penalty for a break in coverage.

But groups that represent people with serious illnesses warned that those Americans could face grave health consequences if they have to wait for a plan to kick in before seeking costly treatments.

Dick Woodruff, the American Cancer Society’s senior vice president of federal advocacy, said in an interview that there are many reasons people could have a gap in coverage. He noted that between 40 and 85 percent of people with cancer stop working when they are receiving treatment, putting them at risk of losing their jobs, and some people may be uninsured at the time of their diagnosis.

“The first six months after diagnosis is when a lot of critical things happen,” Woodruff said, adding that multiple groups have conveyed their concern to Senate Republicans about the change. “I don’t know who he was trying to satisfy with this provision, other than industry.”

Other measures, which were part of the original bill but are now facing intense scrutiny, have also raised questions.

One provision that spells out how the Medicaid program could be converted to a block grant, for example, would allow states to spend any leftover money on an item “that is not related to health care,” as long as they meet “quality standards” set by the Department of Health and Human Services. The state must also ensure that it is spending as much on health care as it has in previous years.

Dee Mahan, who directs Medicaid initiatives for the advocacy group Families USA, said in an interview that the measure, which is not in the House version of the bill, could allow states to play “a shell game with Medicaid money . . . doable on a much larger scale than it was intended for.”

She noted that in April, after Florida received a $1.5 billion authorization from federal officials to fund a program paying hospitals for charity care known as the “low-income pool,” Florida Gov. Rick Scott (R) suggested spending hundreds of millions of dollars on a dike upgrade and tourism promotion.

The language waives a prohibition in the Social Security Act, which bars federal payments to be made “with respect to any amount expended for roads, bridges, stadiums, or any other item or service not covered under a State plan under this title.” Congress has sought on several occasions to bar these kinds of transfers, which Sen. Charles E. Grassley (R-Iowa) described in a 2008 hearing as “a scam.”

A senior Senate GOP aide said Monday that the provision was “an inadvertent error” that arose because the drafting process “was pretty quick.” The staffer, who asked for anonymity because the bill was still being finalized, said the section would be rewritten to clarify the funds could be used only within Medicaid.

Separately, the leaders included language that aims to mollify Sen. Lisa Murkowski (R-Alaska), who has questioned the bill’s impact on people in her state who gained insurance under the ACA’s expansion of Medicaid. The public insurance program traditionally covers low-income, elderly and disabled Americans along with children and pregnant women. Under the 2010 law, 31 states and the District of Columbia have expanded Medicaid to include able-bodied adults earning up to 138 percent of the federal poverty level, leading to the coverage of an additional 11 million people.

The bill calls for a transfer of Medicaid funds from states that provide more-generous benefits, such as New York and California, to those that do not. But it says the requirement to transfer funds “shall not apply to any state that has a population density of less than 15 individuals per square mile,” That would affect just five states: Alaska, Montana, North Dakota, South Dakota and Wyoming.

Medical costs in Alaska are particularly high, in part because so many people there live in remote areas.

Spokespeople for Murkowski and McConnell did not respond to questions about why that provision was included in the measure. Murkowski has voiced skepticism about the way the bill has been crafted in recent weeks, and she has not signaled support for it.

Senators and aides in both parties had been eagerly awaiting the release of the nonpartisan Congressional Budget Office’s report Monday, which concluded that the bill would save $321 billion over the next decade and leave 22 million more Americans uninsured. By measuring the bill’s impact on the federal budget deficit, leaders now have a sense of how much money they have to work with when they consider 11th-hour additions to try to appease the concerns senators have expressed.

For example, Sens. Rob Portman (R-Ohio) and Shelley Moore Capito (R-W.Va.) have been seeking a dedicated $45 billion fund to treat opioid addiction. Sen. Ted Cruz (R-Tex.), meanwhile, has been pushing to eliminate more ACA regulations and allow people to buy insurance policies across state lines.

Still, some remain skeptical that there is enough time to absorb the bill, make substantive changes to it and also hold a final vote, as McConnell is aiming to do this week.

“We’re not going to be able to make the changes to the bill if we’re forced into a vote this week,” Sen. Ron Johnson (R-Wis.) said in a Monday interview with conservative radio host Hugh Hewitt. “We just don’t have time.”

Johnson, like Cruz, has said he does not support the draft of the bill that McConnell released Thursday.

The National Governors Association echoed this point in a bipartisan letter to McConnell on Monday, signed by NGA Chairman Terry McAuliffe (D) of Virginia and its vice chairman for health and human services, Charlie Baker (R) of Massachusetts.

“The nation’s governors are ready to work with leaders in Washington to make health care more accessible and affordable to the people we serve,” they wrote. “However, governors must be given adequate time to determine the impact any health care bill will have on their states and residents, and ensure that the bill does not adversely harm the people we were elected to serve.”

But Republican leaders are putting increasing pressure on the rank and file to swiftly rally behind the bill this week. President Trump called Sen. Rand Paul (R-Ky.) on Monday to discuss his concerns with the bill, according to Paul spokesman Sergio Gor.

“Senator Paul and the president had a productive call, and he reiterated his issues with the current bill — how it isn’t serious repeal and what things he will need to be convinced it can lower costs for Americans,” Gor said. “He remains open to working with the president and his colleagues on making the bill better.”

And Senate Majority Whip John Cornyn (R-Tex.), who previously voiced openness to voting on health care in July, wrote Monday on Twitter that he was “closing the door” on delays. “We need to do it this week before double digit premium increases are announced for next year,” he added.

Amy Goldstein contributed to this report.