Sen. Ted Cruz (R-TX) isn’t backing down from his quixotic quest to defund Obamacare or shut down the government. Far from it, he seems willing to take the Republican Party down in a desire to protect his status as a conservative grassroots hero.

Now that the House has passed a bill to keep government open as long as Obamacare is defunded, the Texas freshman is pressuring his Republican colleagues to filibuster any continuing resolution unless Senate Majority Leader Harry Reid (D-NV) agrees to gut Obamacare. Reid has vowed not to do so. But he needs 60 votes to advance legislation, and Democrats have 54. That means six GOP members are required to help him move a bill to avert a shutdown. Cruz is working to slam that door shut for every Republican.

“I think next week is a time for party unity,” he said on Fox News Sunday. “In my view, Senate Republicans should stand united to stop Harry Reid from changing the House bill and, in particular, from inserting the funding from Obamacare with 51 votes. That’s going to be the fight procedurally whether he’s able to use a straight party line vote, just Democrats, to put Obamacare back.”And what if six Republicans defect and let Reid move the bill? Then they’re cowards who willingly cast votes for Obamacare, Cruz said.

“I’ll tell you, any vote for cloture, any vote to allow Harry Reid to add funding for Obamacare with just a 51-vote threshold,” he said, “is a vote for Obamacare. And I think Senate Republicans are going to stand side by side with Speaker Boehner and House Republicans listening to the people and stopping this train wreck that is Obamacare.”

In plain English, Reid can advance the House bill and strike the defund-Obamacare language in the end with a simple-majority vote. Cruz wants Republicans to withhold their votes for bringing up the bill until he promises a 60-vote threshold for amendments. The awkward part of this strategy is that it requires Republicans to filibuster the House’s continuing resolution (CR). But that’s their only way to keep up the fight.

The plan has the backing of well-funded conservative advocacy groups, who incubated the furor this summer that forced recalcitrant House Republican leaders into this dead-end fight.

“Heritage Action opposes procedural motions that facilitate efforts to strip the defunding language and reserves the right to include such vote(s) on the legislative scorecard,” the activist group said in a statement on Sunday. “If opponents of Obamacare unite against Reid’s procedural power play by denying cloture, the language defunding Obamacare will remain intact, proving that the Senate cannot move a CR that funds Obamacare.”

“If 41 Republicans stand strong and oppose cloture,” said Matt Hoskins, the executive director of the Senate Conservatives Fund, “they can defeat Reid’s plan to fund Obamacare. However, if Republicans waffle and vote for cloture, it will grease the skids for Reid’s plan to fund Obamacare. It’s pretty simple — any Republican who votes for cloture is voting to fund Obamacare.”

The renewed push by Cruz and conservatives also puts the squeeze on Senate Minority Leader Mitch McConnell. The Kentucky Republican is already in a tight spot between fending off an anti-Obamacare GOP challenger for re-election and averting a government shutdown that could hurt the party in the November 2014 elections.

Many Republicans recognize that Cruz and his cohorts are on a fool’s errand. It’s one thing to filibuster and block Reid from advancing a funding bill. But passing a continuing resolution that defunds Obamacare in the Senate requires Reid’s complicity along with the votes of 13 other Democrats. And that’s still not enough: to enact such a bill into law, they’ll need a two-thirds majority in both chambers of Congress to overcome a promised veto from President Barack Obama. It’s a fantasy of the highest order.

“In the United States Senate, we will not repeal or defund Obamacare. We will not. And to think we can is not rational,” Sen. John McCain (R-AZ) said last Thursday on CNN. “To somehow think we are going to defund it is simply not going to happen at this time, and it will, in my opinion, as it did before, harm the American people’s view of the Republican party.”

With McConnell unable to play the role this time around, McCain will likely be Democrats’ go-to Republican in rounding up the six votes. Cruz and the conservative base are making that task much harder by painting a procedural vote to fund the government as a white flag of surrender on Obamacare, which is political poison for Republicans.

The government shuts down next week on Oct. 1 if Congress doesn’t act. Senate Democrats believe that even if they do get six GOP votes, completing the bill may take all week, bringing the country perilously close to a shutdown by the time it ping-pongs back to the House. Polls suggest Republicans, being the party out of power, will be blamed. That means once the lights go out, they’ll have no choice but to fold. The only question is whether Cruz destroys what’s left of the GOP brand in the process by shining a national spotlight on its radical tactics. He’s laying the groundwork to escape from the battle with his reputation in tact by preemptively blaming his colleagues — colleagues who remain skeptical of his plan.

“Tactics and strategies ought to be based on what the real world is. We do not have the political power to do this,” Sen. Tom Coburn (R-OK) said Sunday on CBS’ “Face The Nation.” “So we’re not about to shut the government down over the fact that we cannot, only controlling one house of Congress, tell the president that we’re not going to fund any portion of this [health care law]. Because we can’t do that.”