Some Senate Republicans aren’t ruling out including a repeal of Obamacare’s individual mandate in a tax reform bill even though leaders of the House effort have nixed the idea in their legislation.

The House is expected to release its tax reform legislation on Wednesday and the Senate some time later. Rep. Kevin Brady, R-Texas, head of the House Ways and Means Committee and leading the House tax reform effort, said Tuesday that the bill wouldn’t include a repeal of Obamacare’s mandate that every individual have insurance or pay a penalty.

But Brady’s counterpart in the Senate, Finance Chairman Orrin Hatch, R-Utah, wouldn’t say whether the Senate tax bill would include the repeal. “We’ll have to see. We are still working,” he said.

Sen. John Thune, R-S.D., the third-ranking GOP senator, said that he doubts it will be in the bill.

“I wouldn’t want to rule it out,” he added. “There is some interest among our members on that issue.”

Sen. Tom Cotton, R-Ark., told reporters Monday he would like to see repeal in the tax package.

The request comes after several failed votes to repeal Obamacare, another key legislative priority for Republicans.

The open question over the mandate also brings up a thorny issue with tax reform: how to reconcile competing versions in the House and Senate.

Thune said the separate bills would be on “somewhat parallel tracks.” The reason is to meet a deadline to pass an overhaul of the tax code by the end of the year.

“If we waited for the House to get all the way through with it we would have a hard time being able to get it queued up in a way that would enable us to get it through and hopefully on the president’s desk before the end of the year,” he said. “By the time we start marking up [our bill in committee] hopefully they will be on the floor.”

Thune said Republicans would try to “sync this up as much as we can.”

However, he said the GOP understands there are going to be “perhaps differences between the two bills that our members might like things in the House bill and theirs might like things in the Senate bill.”

Some senators are skeptical of adding a repeal of the individual mandate to the bill, wanting to keep the focus on reforming the tax code.

“If there is a way to do it, I would be open to it but I am not going to push it because we are gonna focus on taxes and the tax reduction plan,” said Sen. Mike Rounds, R-S.D. “Will we continue to work on continuing to eliminate the mandate requirements? Yes, but whether or not that is the correct vehicle I am not sure.”