Washington (CNN) These last frenzied hours before Republicans put up their health care reform proposal are going to bring a lot of political excitement and good old-fashioned Washington spin and speculation. Lawmakers who support the bill will say they do have the votes to pass the bill. Lawmakers who oppose it will say they don't have the votes.

Before we speculate, here's what we know:

The setup: The only thing we really know is that House Speaker Paul Ryan has said a vote on the bill will take place Thursday and that no Democrats are going to support it.

The math: Ryan promised Republicans would get 216 votes by Thursday. With 5 vacant seats, they can afford to lose 21 of their own members if they want it to pass the House. It faces an equally uncertain future in the Senate, but that's something for speculation on another day.

With that, and after you read more from CNN's full coverage of the Obamacare repeal effort , here are three possible scenarios to explain their strategy.

1. They don't have the votes, but they can get them

If they're successful, Congratulations! More negotiation. Only now, with the Senate.

Ryan was confident when he promised last week they'd reach 216 votes and pass the bill, sending it off to the Senate and then for further revision in a conference committee. But conservatives in the House Freedom Caucus have said there are enough votes to defeat the bill. So our first scenario is that both groups are true to their word and that Republican leaders and President Donald Trump are working to change minds. They could employ small tweaks to the bill's language, something they've already done once. They could offer unrelated treats to bring specific lawmakers on board. They can threaten the entire caucus, as Trump did Wednesday, that if they fail to deliver on their promise to repeal health reform, they'll lose their majority.

Ryan and his lieutenants have been clear -- this bill, which frustrates both conservatives and moderates for very different reasons, is Republicans' one-and-only shot to repeal Obamacare.

"This is the chance," Ryan said during a theatrical presentation earlier this month meant to make the bill more palatable. "This is a once-in-a-lifetime opportunity."

At the end of the day that might be the most compelling argument for a lot of members who don't think the bill goes far enough or are uncomfortable with what it does to states on Medicaid.

If they can scrape their way to 216, the bill heads to the Senate, where conservative senators have pledged to oppose it and moderates want to protect Obamacare's Medicaid expansion.

2. They don't have the votes, and they're not going to get them

Now what? It would be a debilitating blow to Trump and Ryan's aggressive agenda. They'd like to use cost savings from the Obamacare repeal measure to move toward tax reform. And from there, the border wall and infrastructure projects loom. Expending political capital on a failed measure and suffering the setback could have long-lasting repercussions for both leaders.

3. They know they don't have the votes, and they're going to take the vote anyway

If Ryan suddenly pulls the bill or if he goes ahead with the vote and allows it to fail, does that mean there is no hope for Republicans to repeal Obamacare? Yes. Mostly dead, at least. Let's recall the example of the Wall Street bailout, which was so controversial and unpopular back in 2008. That bill failed on its first try. It took a resulting stock market dive and outcry for the bill to finally pass the next time around. You heard what might be the seeds of an argument for pressure at home leading to another effort on CNN this morning when Texas Rep. Pete Sessions said part of the reason the health care reform proposal has not caught on is that Republicans have failed to explain it properly to constituents back home, and so lawmakers are not feeling enough pressure.

Would failing to pass a long-promised Obamacare repeal, even if it is flawed, apply enough pressure to bring Republicans on board down the road?

Republican Rep. @PeteSessions says GOP health care bills is "two-thirds of a good bill," better than Obamacare https://t.co/zNYg8tqyt1 — New Day (@NewDay) March 22, 2017

Trump spokesman Sean Spicer, similarly, pushed the bill during the White House press briefing Wednesday.

"I think there's going to be a price to be paid, but it's going to be with their own voters," Spicer said of Republicans opposing the bill. "And they're going to have to go back and explain to them why they made a commitment to them and then didn't follow through."