WASHINGTON — Senate Republicans delivered another blow in their effort to dismantle the Affordable Care Act when they failed to pass a repeal of the Obama-era law on Wednesday afternoon.

The vote, which is one of many expected during the ongoing health care debate, only garnered the support of 45 Republicans, short of the 50-votes necessary.

Sens. Shelley Moore Capito, R-W.Va., Susan Collins, R-Maine, Dean Heller, R-Nev., and John McCain, R-Ariz., and Rob Portman, R-Ohio, Lisa Murkowski, R-Alaska, and surprisingly Lamar Alexander, R-Tenn., the chair of the Senate Health Committee, joined all Democrats in voting against it. The defeat eliminates the chances of Congress sending a nearly-full repeal of the law to President Donald Trump to sign.

"I don’t think Tennesseans would be comfortable canceling insurance for 22 million Americans, and trusting Congress to find a replacement in two years," Alexander said in a statement after the vote referring to the repeal bill that would have gone into effect in two years. "Pilots like to know where they’re going to land when they take off, and we should too."

The vote was contrary to a seven-year long campaign promise by most Republicans to repeal Obamacare — a point noted by some Republicans. Sen. Ben Sasse, R-Neb., criticized his colleagues for not passing the measure.

"Today’s vote is a major disappointment to people who were promised full repeal. We still have a long, long way to go — both in health policy and in honesty," Sasse wrote in a statement.

It was their second effort to dismantle the current health care law in as many days. Their first attempt to undo the Obama-era law with a vote to partially repeal and replace Obamacare, also failed to pass Tuesday night.

Wednesday's vote was on the same measure that passed both the House and the Senate in 2015 and was vetoed by President Barack Obama.

Conservatives enthusiastically voted for it, but some Republicans, especially moderates, are concerned that it would leave too many people without insurance. They would prefer to have something to replace it with, but Republicans have so far been unable to reach agreement on the details of how to do that. Just 43 Republicans voted for the most recent version of the Senate replacement bill Tuesday night.

Related: Senate Votes Down Repeal and Replace

The Senate will now move on to vote on a series of amendments on individual health care reform measures. Those that pass would then likely be cobbled together into a bill, known as a “skinny” repeal.

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“The end game is to be able to move something at the end of this process across the senate floor that can get 50 votes and get it to conference with the House,” said Sen. John Thune, R-S.D.

Leaders think the end product will likely include a repeal of the tax on medical devices, something that even Democrats don’t like. And GOP leaders hope it will also include a repeal of the mandates that require individuals and employers to purchase insurance.

But Democrats are putting on the full-court press to try and stop even a slimmed-down version of repeal to pass.

While Republicans are trying to figure out what their next iteration of a bill is, Senate Minority Leader Chuck Schumer announced that Democrats would not offer any amendments during the rest of the health care debate until Republicans unveiled their proposal.

"Once the majority leader shows his hand, reveals what his bill will actually be, Democrats will use our opportunity to try to amend the bill," Schumer said on the Senate floor. "But we have to see it first. And we ought to see it soon, in broad daylight, not at the 11th hour. Until we see the real bill, Democrats will offer no further amendments."

Democrats also requested an analysis from the non-partisan Congressional Budget Office of what they think the "skinny repeal" might consist of. The CBO says under the plan 16 million people would lose health insurance and premiums would rise 20 percent.

They also released a letter from a bipartisan group of 10 governors urging Republicans to reject the modified repeal.

"We agree with Senator John McCain that the Senate should 'return to regular order' working across the aisle to 'provide workable solutions to problems Americans are struggling with today," the governors, including Republicans John Kasich of Ohio and Brian Sandoval of Nevada, wrote.

Meanwhile, President Donald Trump continues to publicly pressure Republicans. He singled out Sen. Lisa Murkowski, R-Alaska, in an early morning tweet for voting against yesterday's motion to proceed with the debate. Murkowski joined Sen. Susan Collins, R-Maine, as the only two Republicans to oppose that vote.

Senator @lisamurkowski of the Great State of Alaska really let the Republicans, and our country, down yesterday. Too bad! — Donald J. Trump (@realDonaldTrump) July 26, 2017

Murkowski defended her vote, saying she did what she though was best for Alaska. She said that despite the president seemingly threatening her re-election.

“I am in an position where I'm not looking to a reelection until 2022. That's a long time away. And quite honestly I don't think it's wise to be operating on a daily basis thinking about what a statement or a response that causes you to be fearful of your electoral prospects,” Murkowski told NBC News.

While Republican leaders have been telling their members that a final bill could be worked out in conference with the House of Representatives, two aides said that conference is the least preferable route and is only one of several options.

A conference committee presents a challenge for Republicans because Democrats would be included and would be able to raise objections and slow down the process.

Other options include an informal conference that doesn't include Democrats where Republicans would work out a bill. Another option is for the House to take up whatever the Senate ends up passing, but some members might object to this idea because senators are being told they can get a broader bill in conference.

Sen. Lindsey Graham, R-S.C., said that he is expecting a much more comprehensive bill to come out of conference.

"If it's just a skinny bill ... that will not be success. We're not going to trick our constituents," Graham said.

But others are worried about a conference committee, including Sen. Mike Lee, R-Utah. Conn Carroll, his spokesman, said that Lee is worried about the outcome of a bill that could be written in conference.

A House leadership aide said that it's too early to determine a path forward because the Senate hasn't yet passed anything.

The House appears divided on the next steps, too.

Rep. Mark Meadows, R-N.C., and chair of the conservative House Freedom Caucus, said there's "zero chance" a "skinny" repeal could pass in the House. He said that conference is the only option.

But Rep. Tom MacArthur, R-N.J., a moderate who played a major role in passing the House health care bill, said conference will be "a challenge."

"We had enough trouble getting it out of the House, they’ve had enough trouble getting it out of the Senate. I am not sure how it gets simpler if you put everyone together," MacArthur said.