WASHINGTON (AP) — Ted Cruz and Mike Lee stand as the Senate’s dynamic duo for conservatives, crusading against President Barack Obama’s health care law while infuriating many congressional Republicans with a tactic they consider futile, self-serving and detrimental to the party’s political hopes in 2014.

Cruz, the Texan who’s been anything but a wait-your-turn freshman, and Lee, the tea party-backed giant slayer from Utah’s 2010 election, spent months this summer pressuring Republicans to link any stopgap spending bill to keep the government running with permanently starving President Barack Obama’s health overhaul of money.

The two former Supreme Court clerks are determined to reverse what the conservative court of Chief Justice John Roberts upheld in 2012 — Obama’s signature domestic law.

The senators scored a win Friday when the Republican-led House, pushed by rambunctious rank-and-file members, passed a spending measure that would unravel the law. But the approach faces near-certain defeat in the Democratic-controlled Senate, where lawmakers in both parties complain that Cruz and Lee have pushed a losing cause.

In the meantime, their strategy has roiled many in the GOP, with plenty of public and private carping. House Speaker John Boehner, R-Ohio, subtly challenged Cruz and Lee to back up their words next week.

“I expect my Senate colleagues to be up for the battle,” Boehner said.

Several Republicans complain that the tactic could lead to a government shutdown on Oct. 1, the start of the new budget year, that would undercut the GOP politically as the party faces a Democratic president weakened by missteps on Syria.

They question Cruz and Lee’s uncompromising approach, which has raised money for outside conservative groups and provided them with more than 1 million signatures on a “Defund It” petition; those are names that could be mined for future fundraising. Cruz’s recent political moves have stirred talk of a 2016 presidential run.

Some Republicans privately fume that Cruz and Lee, stars of “Defund Obamacare” ads from the Senate Conservatives Fund, come off as the only two Republicans opposed to the health care law when in fact Republicans were united for months against Obama and the Democrats in trying to head off the law in 2009 and still vehemently oppose it.

Looking ahead to next year’s elections, Republican Sen. Bob Corker said he held a fundraiser at his Tennessee home for the state’s senior senator, Lamar Alexander, a steady conservative who is seeking a third term.

“Now he’s (Alexander) using that money to defend himself against ads that Republicans are helping create,” said Corker said, questioning whether the defund ads were “a thoughtful way of going about changing policy.”

Alexander has countered any misperceptions with a commercial spot that highlights his 23 votes against the health care law, describes him as leading the “conservative fight against Obamacare” and shows his winter 2010 exchange with Obama over premium costs at a White House forum with lawmakers.

The internecine fight, brutally on display in GOP primaries in Kentucky, South Carolina and Tennessee, could undermine the GOP’s legitimate shot at winning a Senate majority next year. Twenty-one Democratic seats are on state ballots next year compared with 14 Republican, and the GOP will need to gain six seats to win control of the 100-member chamber.

“I hate Obamacare,” said Sen. Orrin Hatch, R-Utah. “I think it’s one of the worst things that’s been peddled off on America. I don’t blame anybody for doing what they can to try to kill it, but there should be an end game.”

Sen. Tom Coburn, R-Okla., called the combination of defunding “Obamacare” and the spending bill a “political ploy.”

Still, Cruz and Lee press ahead, with a showdown in the Senate this coming week. Conservatives and tea partyers are ecstatic.

JoAnn Fleming, an activist in the Kingwood Tea Party in East Texas, praised Cruz for his singular quest. She commended him for cutting through the noise, which she defined as “those people in the Republican Party who always have an excuse for not doing the right thing.”

“They think a freshman is just supposed to come to Washington and sit down and shut up, and Ted Cruz is not at all like that,” said Fleming, who also heads the citizen’s advisory committee to the Tea Party Caucus in the Texas Legislature. “We didn’t elect him to go to Washington to just sit down and fall in line with the rest of them. And so he’s done exactly what we sent him to Washington to do.”

Fleming said people lined up three hours to four hours in advance for one of Cruz’ “defund” tour stops this summer in Texas. An activist for 21 years, Fleming said she never saw anything like it.

The 42-year-old Cruz stunned the Republican establishment in 2012, capturing the GOP nomination from Lt. Gov. David Dewhurst, who had the money and the backing of Gov. Rick Perry.

Cruz, a Cuban-American with an Ivy League resume, time as Texas solicitor general and a Supreme Court clerkship with the late Chief Justice William Rehnquist, created headlines in his first few months in the Senate with a fierce challenge to Defense Secretary Chuck Hagel’s nomination.

Cruz promised this past week to do “everything and anything possible to defund Obamacare,” including a possible filibuster, describing the law as a job killer.

Lee said that although the conventional wisdom is Senate Majority Leader Harry Reid, D-Nev., has the votes to stop their effort, “in the meantime, those of us who feel strongly that Obamacare needs to be defunded will continue with our message.”

In several fundraising appeals, Lee has warned that Obama, Democrats, the media and “even some from own party” are lying about his efforts to defund “Obamacare,” saying he’s trying to shut down the government. Not so, says Lee, who argues that he’s trying to keep the government operating and end the health care law.

“The point is Obamacare ought to be able to stand on its own merits,” Lee said. “The law is increasingly unpopular with the American people, causing increasing amount of uncertainty among Americans. Most Americans currently believe that Obamacare’s impact will make their family health care situation worse, not better.”

The health care law and the tea party’s furious response helped propel Lee to Washington in 2010. The 42-year-old Lee, the son of President Ronald Reagan’s solicitor general, Rex Lee, and a former clerk for Supreme Court Justice Samuel Alito, snatched the Senate seat from Republican Sen. Robert Bennett.

He challenged Bennett over the incumbent’s backing for the 2008 financial bailout. Lee has remained steadfast in sticking to his conservative approach without compromise.

“I will not vote for spending legislation that votes for Obamacare,” Lee said.

Cruz and Lee continue to appear in the Senate Conservatives Fund ads, and the organization reported raising $1.8 million so far this year, according to the Federal Election Commission. The ads are running nationwide — in Republican and Democratic leaning states.