In his nine months as a U.S. senator, Texas Republican Ted Cruz has managed to infuriate members of his own party by deriding them as cowards who like to cast meaningless votes while pretending they’re fighting the good fight for conservatives.

“There are a lot of politicians in Washington who love empty symbolic votes. It’s been one of my biggest surprises in the Senate, I guess I wasn’t cynical enough when I arrived here,” Cruz said in late July at the Heritage Foundation. “I didn’t realize how many Republicans love to have a fig leaf vote where they can go and tell their constituents, ‘see I voted to do the right thing.’ The House has voted what 39, 40, 41 times I can’t keep track to repeal Obamacare. Those votes were by and large empty symbolic votes that had zero chance of passing.”The Texas freshman has fired these shots from a comfortable position: a senator representing a deep-red state and member of the minority whose support is not essential to moving any legislation. He’s insulated from the responsibilities of governing; he can freely vote the way he wants (he almost never votes for final passage of a bill) and talk smack about his colleagues without having to take real risks.

But now the freshman senator and his fellow Obamacare defunders, most notably Sen. Mike Lee (R-UT), have found themselves in an unthinkable position. The House granted their wish on Friday and passed legislation that eliminates funding for Obamacare in a bill to keep the government funded, sending the battle to the Senate. That means that for once, these senators have to put up and demonstrate their gravitas. Their first instinct was to concede defeat and slink away in the Senate, but after a furious reaction from House Republicans, they feel renewed pressure to walk the walk.

“I hope that every Senate Republican will stand together and oppose cloture on the bill in order to keep the House bill intact and not let Harry Reid add Obamacare funding back in,” Cruz said in a statement Friday, referring to the GOP’s ability to filibuster.

Lee said that “with a unified Senate Republicans Caucus, we will convince enough Democrats” to agree to defund Obamacare.

Hope, after all, isn’t much of a plan.

“It’s pretty clear they had no plan all along,” said a senior House Republican aide after the vote on Friday. “They already let Senate Democrats leave for the weekend. Where is the action?”

There are a several ways they can actually fight this battle. Senate Democrats ultimately need some Republican votes to advance any continuing resolution: 60 votes are required to begin and end debate; Democrats have 55. One option would be to take to the airwaves and grassroots to raise the heat on fellow Republicans to filibuster until Democratic leaders agree to keep the provision of the House’s bill that defunds Obamacare. Another option for Cruz and his colleagues is to raise a ruckus and demand an open debate, creating an opportunity to mount endless talking filibusters until Democrats fold.

But these options would risk a government shutdown as the eyes of the nation look upon them, subjecting them to fierce criticism for grinding federal services to a halt for the purpose of waging a divisive, ideological battle. Even worse, it risks damaging the GOP’s credibility in upcoming elections and placing the blame squarely on them.

One thing is for sure: Cruz and Lee will lose the battle. Democrats vow not to defund Obamacare, and even if Congress does so, President Barack Obama has threatened to veto it. The only question is if Cruz and Lee go down fighting and leave it all on the field, or if they relent and reveal that their Obamacare rhetoric was a bluff all along.

If, by some miracle, Senate Republicans are successful in delaying the legislation long enough to face a real government shutdown — the first since 1996 — the party is likely to pay a political price. Cruz has seemed unconcerned about the political blowback of such a scenario, likening a shutdown to an extended weekend in July.

“Republicans are simply postponing for a few days the inevitable choice they must face: pass a clean bill to fund the government, or force a shutdown,” Senate Majority Leader Harry Reid (D-NV) said on Friday. “I have said it before but it seems to bear repeating: the Senate will not pass any bill that defunds or delays Obamacare.”