Updated

The Senate will move forward with a key vote this week on a Republican health bill but it's a mystery what exactly they will be voting on.

It is not yet known whether the legislation will seek to replace President Obama's health care law or simply repeal it.

Sen. John Thune of South Dakota said Sunday that Senate Majority Leader Mitch McConnell will make a decision soon on which bill to bring up for a vote, depending on ongoing discussions with GOP senators. Thune sought to cast this week's initial vote as important but mostly procedural, allowing senators to begin debate and propose amendments.

But he acknowledged senators should be able to know beforehand what bill they will be considering.

Both versions encountered opposition from enough GOP senators to doom the effort, but McConnell, R-Ky., is making a last-gasp attempt this week after Trump insisted that senators not leave town for the August recess without sending him some kind of health overhaul bill to sign.

Some senators told The Wall Street Journal that McConnell told them that they would find out before any vote if they will be asked to repeal and replace.

Sen. Rand Paul, R-Ky., who called the bill a “porkfest” in an interview said that the current legislation will not work.

“I think it keeps the fundamental flaw of ObamaCare, the death spiral will continue and we’re going to subsidize it,” Paul, the Kentucky Republican, told Maria Bartiromo on “Sunday Morning Futures.”

McConnell, was making a last-gasp effort to resuscitate the legislation, cannot afford to lose any more than two Republican votes, The Journal reported.

President Trump tweeted on Sunday, "If Republicans don't Repeal and Replace the disastrous ObamaCare, the repercussions will be far greater than any of them understand!"

Trump has had a complicated relationship with the Republican Party, but GOP lawmakers have continued to be generally supportive of the president, even as his approval ratings slip.

“There’s less money from the government going to poor people, but there’s more money from the government going to rich people who run insurance companies,” Paul explained. “I think when voters find out that Republicans gave billions of dollars to rich insurance companies and took money away from poor people getting Medicaid, I think that’s a disaster.”

Still, at least two Republican senators Sunday appeared to reaffirm their intention to vote against the procedural motion if it involved the latest version of the GOP's repeal-and-replace bill.

Moderate Sen. Susan Collins of Maine said she continued to have concerns about reductions to Medicaid and criticized the Republican process, saying lawmakers were being unfairly kept in the dark. Under McConnell's plan, 22 million more people would become uninsured by 2026, many of them Medicaid recipients. She wants to hold public hearings and work with Democrats.

The Associated Press contributed to this report