Senate Whip John Cornyn said Thursday that Republicans don't have the "luxury" of knowing what's in a healthcare bill to repeal and replace Obamacare before voting on it.

Cornyn said a procedural vote is scheduled for early next week on Obamacare repeal but the outcome remains in doubt.

The procedural vote will be on a House bill that passed in May but will quickly be stripped. What it will be replaced with is not known at this time, with Senate leadership possibly putting up a 2015 bill that guts Obamacare but leaves it intact for a few years while Republicans craft a replacement or a bill that partially repeals and immediately replaces Obamacare.

The Texas Republican said that members should vote for the motion to proceed to debate because there can be endless amendments to the bill. The senator was then asked if senators should know what the plan is before they vote on it.

"That's a luxury we don't have," Cornyn responded.

A spokesman later clarified that Cornyn was referring to the open amendment process.

Cornyn said the vote next week will be to start debate and then there can be endless amendments. Leadership is expected to offer a first amendment with either the Obamacare replacement bill called the Better Care Reconciliation Act or the 2015 repeal bill.

Neither option has enough support now to pass the Senate, and it is not clear if Senate leaders will bring up either bill if they know it will fail. Senate leadership hosted about 20 lawmakers Wednesday night to discuss their differences, but no breakthrough emerged.

But Cornyn is banking on senators being at least willing to start debate by voting for a motion to proceed on the House bill.

"You can't debate something that you can't initiate the debate on," he said.

However, several other members said the leadership will bring up whatever they can get 50 votes on.

Cornyn then said that he hopes Sen. John McCain, R-Ariz., will be back in time for the vote. McCain has been recovering from a surgery on a blood clot above his eye, and it was revealed Wednesday night that he was diagnosed with an aggressive brain tumor.

Some senators said that they expect to get an advance warning of which bill the Senate plans to take up before they have to vote.

"We will know what the first amendment is before the motion to proceed; we were specifically told that," Cassidy said. "It won't be the morning of sort of thing, it'll be sometime in advance."

• Washington Examiner healthcare writer Kimberly Leonard contributed to this report.