Senators voted, 51-50, Tuesday afternoon on a motion to proceed with debate on a healthcare bill when Vice President Mike Pence broke a tie with the decisive vote.

Along with all 48 Democrats, Sens. Susan Collins (R-Maine) and Lisa Murkowski (R-Alaska) voted against the motion to proceed with debate. The duo's dissent from Sen. Majority Leader Mitch McConnell (R-Ky.) illustrates the tip of a GOP iceberg that is rife with splits between conservative and moderate lawmakers.

Sen. John McCain (R-Ariz.) received a standing ovation as he flew in to cast a pivotal vote for the motion following an absence as he fights brain cancer. McCain spoke to his fellow Senators after the vote, urging them to work together to pass meaningful legislation.

"Why don't we try the old way of legislating in the Senate, the way our rules and customs encourage us to act?" McCain said. "We're not getting much done apart. I don't think any of us feels very proud of our incapacity. Merely preventing your political opponents from doing what they want isn’t the most inspiring work."

Following Tuesday's vote, the future of the GOP healthcare effort to overturn the Affordable Care Act (aka Obamacare) is murky at best.

"It is unclear whether Republicans will have the votes they need to uproot the law that has provided health insurance to millions of Americans," The New York Times reported. "The Senate will now begin debating, amending and ultimately voting in the coming days on legislation that would have a profound impact on the American health care system."

That medical system accounts for about one-sixth of the U.S. economy, estimated to be $18.46 trillion last year.

White House pressure preceded the Senate vote.

"Any senator who votes against starting debate is telling Americans that you are fine with the Obamacare nightmare," President Donald Trump said Monday. The president made overturning Obamacare a central plank on his successful run for the White House.

But how nightmarish is Obamacare? In contrast to Trump's view, the NY Times reported strong public support for the ACA, opening with sources who at first stridently opposed the federal healthcare law but later came to approve it.

Opposition from the rock-solid blue Golden State swiftly ensued after the Tuesday vote.

"It's outrageous and irresponsible that the Senate voted to proceed to final passage on such a devastating and destructive bill, without any committee consideration, expert testimony, hearings or even a public draft of what they will vote on," said Anthony Wright, executive director of Health Access California.

In a post-vote statement, National Nurses United, a labor union, said while it continues to oppose Senate Republican efforts to uproot the ACA, Democrats should admit worries about ACA failings as a sign to support a Medicare for all Americans.

"Every Republican bill pushed first in the House and now the Senate is a disaster that would punish tens of millions of Americans with higher healthcare costs and lack of coverage," said NNU Co-President Jean Ross, RN.

The GOP debate to overturn Obamacare promises to be lively.

"I voted for the motion to proceed to allow debate to continue and amendments to be offered," McCain said. "I will not vote for the bill as it is today."