A victory would go a long way to silence his critics -- including President Donald Trump
-- who charge the Senate majority leader failed to accomplish the top Republican promise to voters when the GOP-controlled Senate fell one vote shy
of ditching Obamacare this summer. It could also buffer the Kentucky Republican against grassroots detractors unhappy that Trump, in some instances, has started to go around GOP leaders on the Hill to cut deals with Democrats
on fiscal matters and possibly immigration issues.
But a second loss on health care, which is very possible, could again raise doubts about McConnell's leadership and create new tension in his relationship with Trump at a time they need to join forces to advance a major tax overhaul
and other legislation.
While momentum for the new repeal bill has gained sudden and unexpected momentum
in the last week, it remains highly uncertain it can get the 50 votes it would need to pass, a threshold previous bills failed to reach despite months of intense negotiations. And McConnell's conference seemingly remains just as divided as before with several moderates from states that expanded Medicaid under Obamacare wary of the impact the new bill's block grant structure will have on their constituents.
"There is still a lot of work to be done," Sen. Shelley Moore Capito of West Virginia said after a closed-door meeting Tuesday where McConnell, Vice President Mike Pence and other supporters of the bill pitched reluctant members to get on board.
McConnell's allies in the Senate defended the leader's handling of health care. They noted that he lived up to his reputation as a great Senate strategist when he cobbled together 49 of 52 Republican votes for the repeal bill this summer, a feat one described as "remarkable" even though it failed.
Sen. Pat Roberts, R-Kansas, said he is concerned about "this whole business of overly criticizing the leadership."
But he acknowledged that it's hard to explain that to critics after the health care bill went down.
"When you're explaining, you're losing," he said.
"It's very complicated both substantively and politically," said Sen. Rob Portman, who is one of those Republicans weighing how the new bill will affect his home state of Ohio. "It falls on all of us not just Mitch McConnell."
Keenly aware that another defeat on health care could be politically disastrous and a major setback for the GOP's upcoming agenda -- including passage of the tax code overhaul -- McConnell went to great lengths to avoid promising a floor vote on the new repeal bill when he answered questions from reporters.
"If we were going to go forward we would have to act before September 30," he said. "We're in the process of discussing all of this."
Republicans took a detour from drafting the tax reform legislation last week when a fresh push to try again to repeal Obamacare grew organically from GOP rank-and-file members at a private GOP conference meeting. The bill was drafted outside of the GOP leadership and health care committee structure but McConnell and his leadership team have fully embraced it as they work to recover from their stunning defeat this summer.
GOP leaders know the stakes are high.
Sen. Roy Blunt of Missouri, a member of McConnell's leadership team, said regardless of what happens with the new health care bill, passing a tax bill is "critical" to Republicans maintaining their majority.
"I think a win is important for all of us but I think what we're doing with health care shows we're continuing to do our best," Blunt told CNN. "I do think win or lose on the health care vote, the tax vote is critical for us and our majority."