After meeting with Vice President-elect Mike Pence on Tuesday to hash out plans to repeal Obamacare, top Senate Republicans are no closer to resolving an issue that’s splintering the GOP heading into the start of Donald Trump’s presidency: how long to give themselves to replace the law.

Pence communicated that the incoming administration is prepared to work closely with Congress on the issue, senators said, but did not dictate how long the transition period should last. That decision will affect millions of Americans’ health care and send insurance companies scrambling to adjust.

“The view on that probably is in a constant state of evolution, based on who you talk to,” said Sen. John Thune of South Dakota, the No. 3 GOP leader. “The question is: What’s that duration? Structurally, it’s at this point an open question. We’re hoping to get some direction.”

The only firm plans are for the Senate to kick off the repeal effort as soon as Jan. 3 by passing a budget resolution — Senate Majority Leader Mitch McConnell is calling it the “Obamacare repeal resolution” — that sets the table to repeal the Affordable Care Act on a simple majority vote. Then, shortly after Trump is sworn in, Republicans aim to have a repeal bill on his desk to sign.

It’s what comes after that moment of catharsis that Republicans are struggling with.

Lawmakers have proposed putting off the effective date of repeal from as little as six months to as long as three years to come up with a replacement — and give insurance markets a chance to prepare. Several senators suggested at the meeting with Pence that additional measures from Congress or the administration may be needed to address rising insurance premiums and avoid roiling the insurance markets in the period between repeal and replace, attendees said.

The length of the transition is pitting hard-line conservatives such as Sen. Ted Cruz and members of the House Freedom Caucus, who favor a relatively speedy replacement, against Senate leaders who are pushing the three-year option.

“It took six years to get into this mess; it’s going to take us a while to get out of it,” said Senate Majority Whip John Cornyn (R-Texas). “One thing I know for sure is we can’t fail to deliver on the promise to repeal Obamacare.”

“We would like three years, but in the House, [some] insist on two,” said Sen. Orrin Hatch (R-Utah), who chairs the Senate Finance Committee.

Incoming House Freedom Caucus Chairman Mark Meadows (R-N.C.) said the Senate’s approach will meet “major resistance,” particularly after the Senate passed a bill in 2015 with a two-year delay that was vetoed by President Barack Obama. Some conservatives believe a transition could happen in as little as six months.

“The sooner we can get rid of it, the better,” said Rep. Jim Jordan (R-Ohio), the outgoing leader of the Freedom Caucus.

“The Democrats passed it in 14 months,” added Rep. Andy Harris (R-Md.). “I’m not going to vote for anything that’s longer than two years.”

Asked to respond to that resistance to a longer transition, Cornyn said: “I don’t know what the basis is for their opinion. Obviously, Speaker Ryan’s got his work cut out for him.”

Privately, Republican lawmakers said that a three-year transition could be a major political headache. If such a delay is enacted early next year, repeal would land in the thick of the next presidential primary season. Furthermore, Republicans believe they may have to vote to extend health care subsidies in any Obamacare replacement, which likely would be scored as a tax increase and turn off fiscal conservatives.

Republicans are trying to model their 2017 effort after what passed the Senate in 2015. That bill was carefully crafted to clear the parliamentarian’s ruling and already has a whip count that can pass the chamber. But delaying the transition period beyond two years is opening up the discussion further, with some Republicans now pushing a repeal of the requirement in Obamacare that dictates the minimum menu of benefits that insurance plans must provide.

It’s unclear whether the Senate parliamentarian would allow them to add that to the bill.

“It is very important if we can [add it] because that’s the real back-breaker in this whole thing,” said Rep. Phil Roe (R-Tenn.). “It is what has made the insurance prices so high, because you’re forcing people to cover all this other stuff that they don’t want.”

Pence was diplomatic and deferential during the lunch meeting. Lawmakers are scrutinizing Trump’s past statements on Obamacare, trying to divine what he wants.

“The point that [Pence] really made is that he’s going to work closely with us. He’s going to be up here working together with us,” said Sen. John Hoeven (R-N.D.). Pence was “not that specific [but said] we have to have a transition and work together.”

While the party struggles over when exactly to disassemble Obamacare, others are trying to focus on developing a replacement as early as possible to give maximum assurance to insurers and voters that they won’t be left in limbo. Republicans will need to immediately begin negotiating with Senate Democrats, who must be involved with any replacement plan to overcome a filibuster.

“It may take awhile … we’ve spent six years acting like the Hatfields and McCoys,” said Sen. Lamar Alexander (R-Tenn.), who chairs the committee with primary oversight over health care. He has said previously he would prefer coming up with a replacement plan in tandem with repeal.

That option is fading, namely because it would require stalling on a repeal vote. But Sen. Bob Corker (R-Tenn.) said a long-term delay could also send a dispiriting message to conservatives: “Boy, we’re going to rush in there, and we’re going to do away with this thing … in three years.”

“It’s very doable to replace it and repeal it simultaneously. And that way, you do it while it’s fresh, you do it while it’s on people’s minds, you do it while people are very aware of all of the issues,” said Corker, who says he is undecided on the best approach. “Again, I’m listening.”

Scrambling things even more, 45 Senate Republicans signed on to a bill in 2015 from Cruz that would allow only a six-month transition, which is more in line with what House conservatives want. Cruz declined to comment for this report when asked about his colleagues’ preference for a three-year period.

Sen. Susan Collins (R-Maine) said she has surveyed a number of insurance experts on what would cause the least amount of turmoil. She voted against Obamacare repeal in 2015 after supporting previous iterations because it defunded Planned Parenthood. But she is diving into the latest effort.

“I don’t know the answer. I truly don’t know. I’ve heard estimates from experts ranging from a minimum of two years to five years,” Collins said. “Five years strikes me as too long … but I don’t think you can do this overnight, either.”

Senators said it’s unclear what approach Trump prefers. Absent a clear beacon, GOP lawmakers said they will lean heavily on Rep. Tom Price (R-Ga.), Trump’s nominee to lead the Department of Health and Human Services. While Trump has said he wants to keep parts of Obamacare, such as requiring insurance for pre-existing conditions, Price has been one of the most ardent anti-Obamacare voices in the House.

“It’s quite likely,” said one Republican senator, “that the Trump approach will be the Price approach.”

Rachael Bade contributed to this report.