This drama with the threat of a government shutdown hanging over it all will play out throughout this week, with the showdown vote expected to take place Saturday.
House members adopted the plan Lee and Sen. Ted Cruz, R-Texas, have advocated: They passed a bill last week that would keep the government operating through Dec. 15, while also stripping all funding for the Affordable Care Act.
Now Senate Majority Leader Harry Reid, D-Nev., has declared that bill "dead" and called Lee and his supporters "radicals, extremists and anarchists." He has also staked out a strategy that would allow the Democrats to restore the health reform funding and send the budget bill back to the House.
First, the Senate would vote Thursday to bring up the bill. It takes 60 votes to do so. Lee and his allies are expected to support that.
Then, on Saturday, the Senate would vote to move to final passage, known as cloture. That is also a 60-vote threshold. And if it passes, the Democrats, who control 54 seats, would need only 51 votes to restore funding for Obamacare and pass the bill.
If this scenario plays out, which Lee calls "unacceptable," he hopes all 46 Republicans to block that cloture vote and kill the bill.
"If Republicans are serious about defunding Obamacare, meaning they really want to see it happen, rather than being on the right side of a meaningless vote, then we expect all 46 to stay with us on cloture," said Lee's spokesman Brian Phillips.
But that means blocking a bill that most of them, including Lee, actually support and doing so greatly increases the chance of a government shutdown Oct. 1.
It appears the party is already fracturing on the issue, with Senate Minority Leader Mitch McConnell announcing that he wouldn't follow Lee's lead.
"Senator McConnell supports the House Republicans' bill and will not vote to block it, since it defunds Obamacare and funds the government without increasing spending by a penny. He will also vote against any amendment that attempts to add Obamacare funding back into the House Republicans' bill," said Don Stewart, spokesman for the Kentucky Republican.
Other Senate Republicans have loudly criticized the Lee-Cruz strategy, including Sen. Orrin Hatch, R-Utah, who doesn't see an "end game," assuming the Democrats follow through on their plan to send a funding bill to the House with only hours to act before a shutdown occurs. Hatch has not announced how he will handle this week's votes.
Sen. Bob Corker, R-Tenn., who on Twitter called it "a tactic that will fail and weaken our position," told Politico: "I can't imagine any Republican senators not voting to invoke cloture on a bill they support."
Outside conservative groups such as Heritage Action are warning Republicans that they are watching this vote and may target those åwho don't stand with Lee and Cruz.
The way Lee sees it, he was elected to stop Obamacare using all means necessary, including the threat of a shutdown, though he doesn't want that to occur. And his backers, in Utah and elsewhere, don't care that Republicans don't hold the White House or the Senate.
Appearing on the Senate floor Monday, Lee said: "The Senate majority may have the upper hand, but the American people will and always must have the last word."