There's a possibility that before this month is through, Congress could repeal most of Obamacare.

But don't confuse possible with likely. A proposal picking up steam right now among Republican senators has just as many — if not more — hurdles to get over as did all the other failed attempts to repeal Obamacare this year.

Here's what you need to know about the renewed attempt to repeal Obamacare and what must happen for it to get to President Trump's desk in the next two weeks.

First, a 30-second rundown of the bill: It's spearheaded by Republican Sens. Lindsey O. Graham (S.C.), Bill Cassidy (La.), Ron Johnson (Wis.) and Dean Heller (Nev.), and it would drastically limit the federal government's role in health care.

It proposes dissolving the health insurance marketplaces that Obamacare set up and slicing federal spending for Medicaid to a small fraction of what it is today. Instead, states would get grants from the federal government to establish their own health insurance programs as they see fit.

The bill's four major hurdles

1. Senate Republicans themselves. Republicans are walking the same vote-count tightrope they fell off of in July, when they were one vote short of repealing parts of Obamacare. They can afford only two no votes to pass this legislation, and if this bill ever comes up for a vote, it's going to be close.

The four question marks are the three Republicans who joined all Senate Democrats to vote against a July bill and one other conservative senator who has already indicated that he won't support this version. Even more of a headache: Their opposition is for entirely different reasons.

Sen. Rand Paul (Ky.) doesn't think the bill goes far enough to get rid of Obamacare.

Sens. Lisa Murkowski (Alaska) and Susan Collins (Maine) voted against the July bill in part because they thought it left too many people without a safety net. That's a problem for bill supporters because, if anything, this bill takes July's version even further away from government involvement in health care.

And Sen. John McCain (Ariz.) voted against the earlier bill in part because he thought the process was rushed. Which brings us to our next hurdle.

2. Time is running out. Republicans have only two weeks to do what they couldn't do in six months: pass a major overhaul of the health insurance markets through the Senate and the House and get it to Trump's desk and signed.

They're in a rush because they are trying to pass this with a budget tool called reconciliation, which lets Republicans duck a Senate Democratic filibuster on any legislation that directly affects the government's bottom line.

But the Senate can use this tool only while debating a budget, and that debate ends Oct. 1, when the next fiscal year starts.

McCain in particular has been critical of his colleagues for rushing through major social legislation, though it's not clear if he would vote against this bill for that reason.

“Why did Obamacare fail?” he said Sunday on CBS's “Face the Nation.” “Obamacare was rammed through with Democrats’ votes only.”

3. This version could leave tens of millions of people uninsured. Republicans also can't vote on this bill until the nonpartisan Congressional Budget Office estimates how it would affect insurance markets.

This isn't just a procedural hurdle. CBO scores have doomed past Obamacare repeal deals after the office estimated that tens of millions of people would be uninsured over a decade as a result — as many as 51 million under one version.

And there's every reason to think that this CBO score could be just as high. This bill could leave millions more uninsured than any proposal Congress debated this spring, according to one estimate from the nonpartisan Center on Budget and Policy Priorities. That's in large part because this legislation doesn't require states to spend money to help low- and moderate-income people buy health care.

That will be a hard sell for Republicans representing rural, lower-income areas that depend on help from the federal government to pay for health insurance.

“I did not come to Washington to hurt people,” Sen. Shelley Moore Capito (R-W.Va.) tweeted at one point during this spring's health-care debate.

The CBO says it plans to release a preliminary estimate of the bill's impact “by early next week,” which will clear a procedural hurdle to allow Republicans to vote on the bill, but it won't give them an idea of how many people could lose insurance because of it.

4. Governors: Republican governors were major pressure points this summer for GOP lawmakers on the fence. Of the 13 GOP senators who had concerns about or didn't support the July version of the legislation, eight of their states' governors also didn't support it.

Governors' influence this time could be compounded, given that this proposal would hand almost all health coverage decisions to the states.

That's why Arizona Gov. Doug Ducey's statement Monday afternoon is noteworthy. The Republican said he supports this proposal, which potentially paves the way for at least one July no vote (McCain) to vote yes.

Other governors to watch include Brian Sandoval of Nevada, Bill Walker of Alaska and John Kasich of Ohio, who could influence their states' GOP senators.

Even if McCain can vote "yes," those who want to see Obamacare repealed still need to battle half a dozen skeptical senators, a ticking clock, half a dozen influential Republican governors, and a CBO score that could turn public opinion against the whole thing.

Bottom line: It's possible but not likely that Congress repeals Obamacare in the next two weeks.