Washington (CNN) Senate Republicans have been working behind closed doors on health care for several weeks, and it's now close to do-or-die time if they want to get something done this summer. Here's the state of play:

Is there a bill?

Not yet.

Republican staffers worked throughout the weekend to hammer out a final proposal on health care, with the hope of presenting an updated set of ideas to all GOP members during their Tuesday luncheon. This will be similar to last week, when staffers gave a PowerPoint presentation providing a general outline and menu of options for the GOP proposal, according to several aides. This week's presentation will likely be more definitive.

But there won't be an actual bill to read.

Asked if there would be a bill to show senators at the GOP lunch Tuesday, Senate Majority Whip John Cornyn said simply, "No."

One GOP aide anticipated the meeting would be a red-light, green-light, yellow-light situation, where committee staff will get feedback from members and then determine if they are where they need to be to transform proposals into legislative text. Tuesday is important because Republicans don't have a lot of time to keep hashing out ideas.

We asked Sen. Orrin Hatch, R-Utah if it was a "paricularly big day" for the Senate. His response?

"Every day is a big day in the process."

Timelines

Senate Majority Leader Mitch McConnell wants this voted on before the July 4 recess.

In order to do that, they need to have a proposal to the Congressional Budget Office by early this week at the latest, according to two senior GOP aides. The scoring process is aided by the fact that staffers working on the bill have been passing draft language back and forth with CBO staff in recent days, but it's still not a fast turnaround. Including today, the Senate is only scheduled to be in session 15 more days before the July 4 recess.

All that matters

McConnell can afford to lose two -- TWO -- Republicans here.

He's trying to thread a needle that is extraordinarily difficult to pull off. Think about how painful this process was for House Speaker Paul Ryan. He could lose 21 votes. McConnell can only lose two.

Public not invited

This is all being done behind closed doors.

There's no way around it -- there are no hearings. No legislative language is leaking. Details are sparse. Many Senate aides (and some senators) are in the dark on the most in-the-weeds provisions. (Many more plead ignorance to protect the negotiations themselves.)

It is likely to remain this way even after a proposal is sent to CBO, according to aides. It's possible that leadership does not release a draft publicly so that members can continue to give feedback.

Top GOP aides are keenly aware of what will happen when this thing hits the light of day and are attempting to forestall that as long as possible.

What's in the bill

A better way to phrase this would be, what are the menu of options being considered?

The hangups aren't new -- you'll remember them quite well from the House fight. But these battles are far more pitched and problematic.

Medicaid expansion -- Or when to phase it out. McConnell has pitched three years. Moderates want seven. They also want a drug/opioid rehab fund in there somewhere. The way the rate of growth would be calculated for the overall Medicaid program is still a sticking point for some.

Structure of tax credits -- The House made clear the Senate would have space to add money to and expand the reach of the AHCA's tax credits, and that's what is happening. But the degree to which it does is crucial for both sides. Go too far and risk dropping conservatives already wary of it. Don't go far enough, goodbye moderates.

How far to cut back the ACA's regulatory infrastructure -- This is, once again, the state waiver issue. Senate leaders announced last week they'd keep the House waivers in place, save for community rating. That is a nonstarter for some conservatives.

New issues:

A call for some sort of stabilization multibillion-dollar fund for ailing markets in the near term. This is a bubbling proposal with some significant backers, but it's unclear how it would be formulated or finance or whether it could fly.

Obamacare taxes -- There are discussions to keep them in place for a period in order to finance additions to the bill (remember, the Senate bill has to include, at a minimum, $133 billion in deficit savings over a decade. Given what they want to add, that's a tough number to hit).

Abortion -- In the House bill, you cannot use government tax credits to purchase insurance plans that cover abortion in most cases. But the parliamentarian has alerted senators that language likely won't be allowed in their bill. That means Republicans will either have to keep the Obamacare subsidy structure they have railed against for years or find some other workaround. WATCH this arcane fight because it could be another place conservatives get rolled.

Senators to watch

Sens. Mike Lee, Ted Cruz and Rand Paul on the right.

Sens. Susan Collins and Lisa Murkowski in the center.

Sens. Dean Heller, Shelley Moore Capito and Rob Portman on the Medicaid expansion side of things.

Who may already be gone

If the bill keeps moving in its current direction, several GOP aides say there's a chance at least two, maybe more, of the more conservative lawmakers in the conference would be firmly in the "no" column.

Where are the outside conservative groups

Not very excited.

They played a huge role in the House fight and are itching to do the same in the Senate. As such, they aren't happy right now, but they're also keenly aware that things could shift back in their direction. That said, conservatives on and off the hill continue to have serious concerns about the direction of the negotiations.

Many fear that moderates are getting WAY too much of what they want, including a so-called glide path for Medicaid, which will give expansion states more federal money for longer than the House's bill did. The Obamacare taxes discussion is something that Club for Growth President David McIntosh said "set off alarm bells" last week. But a lot of Republicans are open to this idea, including senators like South Carolina's Tim Scott.

The Club spent Friday making calls to GOP offices and letting them know that keeping Obamacare taxes was a nonstarter. Outside groups are currently working on putting together a campaign to support the Senate health care bill when it's finished, but McIntosh warned that that campaign can turn on a dime if the Senate announces a bill that runs counter to conservatives' wishes.

Where art thou, Ted Cruz?

Cruz, based on history and his ideological bent, should technically be in the above group. But he's not.

At least not yet.

Why? Great question, but according to several senior GOP aides, Cruz has up to this point not only worked in good faith with all parties, but served as a leader of sorts in that role. Senior aides, many of whom have watched their bosses tangle with Cruz in the past, admit they didn't expect it and aren't totally sure if it will last. But there's no question he has legitimately worked to get to a deal. In the end, that may not matter. But that he's still hanging in and continuing to push behind the scenes to find a deal that gets enough of his colleagues to "yes" is a very interesting element.

One final note

On both the House and Senate side, the best case scenario is *if* the Senate passes this legislation, the House will take it up as is and pass it.

Going to conference is a possibility -- something Ryan reiterated last week. But he also noted that given the tight constraints of the budget reconciliation process, the Senate bill would likely in large part track with what was done in the House. On top of that, conference is something pretty much everyone wants to avoid. It's potentially a huge time-suck and will only put the same painful fights back to the center of the table.

In other words, it's very possible that whatever the Senate passes, if it passes anything at all, will be the final bill that gets to President Donald Trump's desk.

In other words, this is the ball game, folks.