The latest delay for Republicans' Obamacare replacement efforts may further damage the GOP's chances of passing a bill already on the verge of failing.
Or it could give Republican leaders the additional time needed to shape the bill to win over skeptical lawmakers.
On Saturday, Senate Majority Leader Mitch McConnell, R-Ky.,
They needed McCain's vote with two GOP senators — the most they can lose and still have a majority with Vice President Mike Pence's tie-breaking vote — opposing a motion to proceed. It is unclear how long McCain will be away from the Senate, but it will likely be at least a week.
Sen. Rand Paul, R-Ky., the bill's strongest opponent from the party's conservative wing, contended Sunday that the pause could further hurt the bill.
"The longer the bill is out there, the more conservative Republicans are going to discover it is not repeal," Paul, who has argued the plan does not go far enough to repeal the Affordable Care Act, told CBS News.
If Republicans lose one more vote on the current plan, they cannot pass it. Beyond Paul and Sen. Susan Collins, R-Maine, who have vocally opposed the plan, at least six more Republican senators remain undecided and could go either way.
The delay carries multiple risks for Republicans who want to win the support of both moderate and conservative senators who are still undecided about whether to vote for the proposal. Pushing the bill through quickly limited the amount of time that groups opposing the bill could put pressure on swing-vote senators.
But doing so also curbed the amount of time McConnell had to strike deals or make tweaks that would make senators more comfortable voting for it. McConnell now has a bigger time cushion to gather support.
Protesters have spoken out against the highly unpopular Republican Obamacare replacement effort during both the House's passage of a similar version and while the Senate tried to win votes for its own plan. The Senate plan has proven unpopular with voters, making potentially vulnerable GOP senators more hesitant about supporting it.
"Clearly, the delay works against the possibility of passage by the Senate," said Steven Billet, director of the masters program in legislative affairs at George Washington University's Graduate School of Political Management. "It provides more time for opponents to mobilize grass-roots protests."
Senators facing pressure from Republican leadership to support the plan have forces pulling them the other way at home. Republican governors like Brian Sandoval of Nevada and John Kasich of Ohio have fought against the bill, partly because of its rollback of Medicaid expansion. Their influence during the delay could complicate the decision-making for Republican senators from their states: Sen. Dean Heller of Nevada and Sen. Rob Portman of Ohio.
A Congressional Budget Office score on a revised version of the Senate bill is also expected this week, and could help to shape decisions for several undecided senators. A report on the previous version of the bill estimated it would lead to 22 million more Americans uninsured in 2026 — more than enough to make several senators hesitant to support the plan.
Even with the opposition to the plan, Senate leaders can muster the support needed to pass the plan with changes to it. The House did so before it approved its plan in May, adding last-second amendments to win over both conservatives and moderates.
Senate Majority Whip John Cornyn, R-Texas, said Sunday he believes the Senate will vote on the plan when McCain comes back.
"I believe that when we have a full contingent of senators that we'll have that vote and it's important that we do so," he told NBC News.