That legislation has won over more than just the usual suspects. Its 27 cosponsors -- all Republicans -- include Senate Minority Leader Mitch McConnell (R-KY) and Minority Whip John Cornyn (R-TX), both of whom are running for reelection in 2014 and are facing primary challengers from the right.
"We have one last chance to stop this if the White House won't cooperate, and that's through our budgeting process," said Sen. Marco Rubio (R-FL), another cosponsor, who is eager to make nice with the right after his major push for comprehensive immigration reform. "Some will say, 'Well, that's crazy. You are going to shut down the government over Obamacare?' No, what's crazy is moving forward with this thing."
Sen. Mike Lee (R-UT) is escalating the push by circulating a letter promising not to vote to fund the government after Sept. 30, when the lights are set to go out, if Obamacare is not fully defunded. It has reportedly been signed by 15 Republican senators. Lee's office told TPM it plans to release the letter and final list of signatories on Thursday.
Defunding the government over Obamacare is, of course, a pipe dream. Democrats would block any such bill, and President Obama would veto it. And a seasoned veteran like McConnell, who was a senator through the 1990s, is well-aware of the perils of shutting down the government to extract ideological concessions from the party in power.
In fact, when asked Tuesday about the upcoming annual spending bill, McConnell, who has not signed Lee's letter, told reporters he wants to stick by the 2011 budget agreement, which includes funding for Obamacare.
"I think our main goal going into the year-end discussion is to not walk away from the bipartisan agreement that we made two years ago to reduce spending," he said. "My view is that we should do what we promised two years ago, and that'll be my goal going into the final discussions."
The deep-pocketed conservative group Club For Growth issued a statement Wednesday demanding that "[i]f Senator McConnell is committed to defunding ObamaCare, then he should sign the Lee letter." Club President Chris Chocola added, "We are disappointed by rumors that Senate Republican leadership is pressuring Senators not to sign Lee's letter or to remove their names -- they should instead encourage others to sign on."
Although conservatives are pleased with the unabated anti-Obamacare rhetoric emanating from House GOP leaders, Speaker John Boehner (R-OH) admitted back in March that holding must-pass bills hostage to the anti-Obamacare effort isn't feasible.
"Do you want to risk the full faith and credit of the United States over defunding Obamacare?" Boehner told Sean Hannity. "That's a very tough argument to make."