In all likelihood, Senate Republicans face a more daunting ideological divide over Obamacare than their counterparts in the House. There are a number of GOP senators, such as Maine Sen. Susan Collins, Alaska Sen. Lisa Murkowski, Ohio Sen. Rob Portman, and Louisiana Sen. Bill Cassidy, who all have said they are unlikely to support the Medicaid cuts or the potential rollback of pre-existing conditions protections included in the House bill.

Even if the Senate is able to muster 50 votes, there is no guarantee many of the conservative Republicans in the House who voted for the recently-approved repeal bill will support the Senate version, particularly if they perceive it as too liberal.

The final complication comes from the finances. If Republicans hope to get a bill through the Senate, they will have to do so through reconciliation, a maneuver that allows them to avoid the typical 60-vote requirement to end a filibuster. However, reconciliation is only possible if the Senate parliamentarian rules that the bill will reduce the budget deficit.

All of the legislative crafting is taking place behind closed doors, as a working group of 13 GOP senators work to craft a bill. The Senate Health Committee, for instance, will not be holding hearings on the matter until there a bill is ready.

The 13 members of the health care working group, however, does not include any women or any of the most moderate members of the GOP caucus who have raised the most pointed objections to the House bill. It is up to them to anticipate objections from the moderate wing when the bill materializes.

Some on the right believe scrapping Obamacare regulations are absolutely critical to driving down premiums. Giving states the discretion to eliminate pre-existing conditions protections or to allow insurers to sell plans that don't include certain benefits, such as pregnancy care, will lower costs, they argue.

"I think we're going to leave it up to consumer to decide what they want to buy and what they need, so we're going to eliminate mandates, not add them," Sen. John Cornyn, R-Texas, the majority whip, told CNN recently.

However, the public outcry in response to those changes have made some Republicans in the Senate very reluctant to include them in their own bill.

Cassidy, who along with Collins has floated an alternative proposal that would allow states to maintain much of the ACA, including Medicaid expansion, recently spoke on the Senate floor about the importance of a bill that would pass "the Jimmy Kimmel test," a reference to the impassioned plea by the late night host to guarantee those with pre-existing conditions have access to care.

"(McConnell will) have to make some decisions. I'm sure it will be with the recommendation and input from our members, but there will come a point in which we've talked some of this stuff to death," Sen. John Thune, R-S.D., tells Politico. "He's made it very clear, at the end of this we're going to have to vote."

Senators have said it will take a while before a bill is ready, suggesting that legislation won't surface until well into the summer, at the earliest.

Democrats, meanwhile, are confident that they can either stop the repeal effort or make the Republicans pay dearly if the bill passes. Angry constituents confronting Republican lawmakers and polls showing growing support for Obamacare and rock-bottom support for the GOP repeal bill has Democrats salivating about the 2018 midterm election.

Sen. Chris Murphy, D-Conn., warns his party not to let the ongoing Russia investigation distract it from its core domestic policy priority.

"My worry is that this story still dominates the headlines and provides cloud cover for Republicans who are rewriting the American healthcare system with nobody watching," he said recently. "We can make Republicans' life a living hell if they put a bill on the floor that looks like the House proposal. But we need to be ready."