Sen. Bill Cassidy said he welcomes the possibility that blue states could voluntarily create their own individual mandates or enact other measures in response to Congress repealing the penalties from Obamacare.

"Our big thing about federalism is that states are quite capable of doing that," said Cassidy, a Louisiana Republican who has pressed for Congress to pass an Obamacare overhaul bill he co-introduced, known as Graham-Cassidy-Heller-Johnson.

His healthcare bill would take funding from Obamacare and transfer it to states so they could set up their own healthcare systems. Cassidy in the past has proposed various ways that states could implement their own healthcare plans to get more people covered, such as by creating an auto-enrollment system by which people who are uninsured would receive catastrophic coverage.

"I think auto-enrollment is a fantastic idea and I think states should have the ability to do that," he told the Washington Examiner Monday.

"There are a lot of ways that states can enroll people," he continued, noting programs such as Medicaid were attractive to people for other reasons than a mandate, which he said was ineffective.

The individual mandate requires people to obtain health insurance or pay a fine. Insurers have urged Congress not to repeal the mandate without providing a replacement, such as a waiting period, saying that otherwise premiums would rise and more insurers would leave the exchanges.

Obamacare requires insurers to provide coverage to people with pre-existing illnesses, without charging them more — a provision they say is balanced out by creating some impetus for less costly enrollees to sign up for coverage.

Republicans have dismissed those concerns, pointing to the mandate's unpopularity and shedding doubt on projections about its effects.

A Congressional Budget Office report estimated that under Obamacare about 24 million people would be enrolled in the exchanges by 2016, but that number was closer to 12 million at the end of that year's open enrollment. Some of that has been attributed to the false projection that employers would send their workers to the exchanges for coverage, while others have noted that potential customers who are younger and healthier, and over the age of 26, have been slower to enroll in Obamacare coverage than other age groups.

Proponents of the individual mandate point to these results as evidence that the mandate needs to be made stronger, such as through closing exemptions, rather than repealed. A bill Republicans considered this year would have implemented a waiting period for those who failed to get covered outside of designated enrollment times.

Regardless, Republicans are poised this week to repeal the individual mandate as part of their tax overhaul bill, the Tax Cuts and Jobs Act, without a replacement. They have said they expect President Trump will sign it by Christmas.

Some pro-Obamacare states are expected to act in response. Massachusetts already has an individual mandate, and the District of Columbia and states such as California and Maryland have begun conversations about implementing their own.

Nevada allows people to sign up for private, off-exchange health insurance at any time during the year, but makes residents wait 90 days to receive coverage. Hawaii has had an employer mandate that has been in place since the 1970s, which requires employers to provide coverage to people they employ for at least 20 hours a week.

"There are a lot of ways to do it," Cassidy said, referring to a potential impetus to get more people covered by health insurance. "Folks who are negative just don't think about it."

The Graham-Cassidy bill failed to gain traction this year but Trump, House Speaker Paul Ryan, R-Wis., and Sen. John Thune, R-S.D., the chamber's third-ranking Republican, have told reporters they intend to return to healthcare in 2018.

CBO has projected the individual mandate repeal would result in 13 million more people becoming uninsured and it would save the federal government $338 billion over a decade. The nonpartisan agency is re-evaluating its methods, and a Standard and Poor analysis pegged the projection at 5 million people without insurance or fewer.

Cassidy said he wasn't concerned about the funding being used for the tax bill rather than as funding for his healthcare bill, noting that a government spending bill that would include Obamacare provisions was ahead. Senate leaders have pledged to pass a bill that would fund cost-sharing reduction subsidies, which help pay for the out-of-pocket medical expenses of low-income people, and to fund a reinsurance program that would pay for medical expenses of the most expensive enrollees.

Both are intended to lower premiums and expected to be included in an end-of-year spending bill facing a Friday deadline.

"You really don't know how it's going to play," said Cassidy, who supports both measures on Obamacare. "I think before you decide the next step you've got to get a lay of the land."