Senate Majority Leader Mitch McConnell (R-Ky.) appears to be blundering into a healthcare vote this week, despite not having a deal on a Senate healthcare bill.

Public struggles aside, McConnell actually does have a plan: pin down fellow Republican senators on their seven-year-old promise to repeal ObamaCare.

McConnell told activists from Tea Party Patriots, FreedomWorks and Americans for Limited Government during a Monday meeting at the Capitol that a key procedural vote will happen Tuesday afternoon.

The motion to proceed needs the backing of 50 senators to pass - assuming Vice President Pence breaks a tie - and it will be close.

Jenny Beth Martin, the co-founder of the grassroots group Tea Party Patriots, said McConnell is pushing very hard on getting members to vote for the motion but did not appear to have it in hand as of Monday afternoon.

"His message is senators need to be for the motion to proceed or they're for the status quo," said Martin, who attended the meeting. "He would not be pushing it so hard, probably, if he had the votes lined up already."

But even if McConnell has enough votes to proceed to legislation on the floor, getting 50 senators to yes on a final vote will be much harder.

There's a slim chance McConnell may pull together a last-minute deal to repeal and replace core elements of ObamaCare.

At a minimum, McConnell wants to show potential critics that there aren't enough votes in the Senate for options A, B or C: the House-passed American Health Care Act, the revised Senate version of that bill or a straight repeal measure similar to what then-President Obama vetoed in 2016.

Once that's demonstrated, the GOP can move on to other issues, including tax reform.

"Sometimes you have to stand up and be counted. You have to have a clarifying vote, and McConnell has done that before," said a Senate GOP aide.

An Associated Press-NORC Center for Public Affairs Research poll released last week found that 27 percent of Republicans favor immediate repeal of ObamaCare, while 54 percent want to repeal the law once there's agreement on replacement legislation.

McConnell employed a similar strategy shortly after becoming majority leader in 2015 when he scheduled votes on bills defunding Obama's executive actions on immigration to prove to conservatives that they lacked support in the upper chamber.

Once he overcame that hurdle, he was able to negotiate a deal to avert a partial government shutdown.

Senate aides expect the procedural vote to begin the healthcare debate to happen Tuesday.

Sen. John McCain (R-Ariz.), who was diagnosed last week with brain cancer, will be back in town for the vote, his office announced late Monday. But it's unclear how he'll vote on the motion to proceed.

Sen. Susan Collins (R-Maine) recently said she would vote against the motion to proceed to the revised Senate bill and expressed strong opposition last week to the repeal-only measure that passed the Senate and House at the end of 2015.

She criticized Senate Republican leaders over the weekend for kicking off the debate without a clear picture of what lawmakers will vote on this week.

"I don't think that's a good approach to facing legislation that affects millions of people and one-sixth of our economy," she said on CBS's "Face the Nation."

Conservative Sen. Rand Paul's (R-Ky.) vote is up in the air as well.

He wrote in an op-ed for The Hill Monday that he will vote for the motion to proceed if it sets up a subsequent vote on a clean bill to repeal as much of ObamaCare as possible, similar to what passed in 2015.

But Paul warned that if GOP leaders decide to move first to "a pork-laden bill that doesn't repeal ObamaCare" - a reference to the revised Senate bill - "I won't vote to proceed to the floor."

Another key vote, conservative Sen. Mike Lee (R-Utah), was undecided as of Monday afternoon, according to his spokesman.

McConnell is negotiating with Senate moderates from states that expanded Medicaid enrollment to allow the debate to go forward.

Sources familiar with the talks say there's a proposal to steer tens of billions of dollars in additional assistance to states that accepted ObamaCare's Medicaid expansion.

One Republican source last week said Senate GOP leaders were prepared to offer an additional $200 billion to Medicaid-expansion states to help low-income people who fall out of Medicaid coverage, but that number may come down substantially because of a potential backlash from conservatives.

Even though McConnell agreed to add $70 billion to a state innovation and stabilization fund and $45 billion to treat opioid addiction in the latest public Senate draft, several moderates still worry the bill will hurt their constituents.

But Sen. Rob Portman (R-Ohio), a key moderate in the Medicaid talks, says he's open to at least starting the floor debate - a good sign for McConnell.

Outside groups are ramping up pressure on wavering senators to allow the debate to move forward.

Tea Party Patriots delivered a letter Monday to Senate offices reminding them that Republicans won the House and Senate by promising to repeal and replace ObamaCare.

"The American people did not give Republicans control of government to simply fix ObamaCare. The American people gave Republicans control of government to repeal ObamaCare - and failure is not an option," the group wrote in a letter to every GOP senator that listed activists in their home states who want repeal.

It's already clear there are not enough votes to pass the House's American Health Care Act or something along the lines of the 2015 bill that would repeal as much of ObamaCare as possible and set up a two-year period to craft a replacement.

The Senate parliamentarian dealt a blow to the legislation when she advised that several provisions in it failed to comply with Senate rules, including language defunding Planned Parenthood for a year - a must-have for many conservatives.

The 2015 repeal-only bill, however, included language defunding Planned Parenthood. GOP aides expressed confidence Monday that the language could be modified to meet the Senate's stringent Byrd Rule.

Conservative Sen. Ted Cruz (R-Texas) suggested earlier this year that the Republican presiding as chairman of the Senate could ignore the parliamentarian's advice, but that idea has little support within the broader Senate GOP conference.