Refusing to budge in their assault on the new health care law, U.S. House Republicans were poised late Saturday to delay much of the law for a year as a condition to keep the government running, with a partial shutdown looking ever more likely.

Senate Democrats and President Barack Obama have said they will not accept any tinkering with the Affordable Care Act as a price for avoiding a shutdown when government funding expires on Tuesday. If neither side blinks, many government services will grind to a halt, except for those deemed essential for health and safety, as hundreds of thousands of civilian workers will be furloughed.

The charge to attack the law known as Obamacare has been led in the House by Rep. Tom Graves, a Republican from Ranger who has rallied his most conservative colleagues to his side time and again to force House leadership’s hand.

Graves said his proposals have “been a valuable tool that leadership has been able to use to bring the (GOP) conference together and, quite frankly, we’ve been united more so in the last couple weeks than in previous months.”

On Friday, Graves got 61 Republicans to sign onto a one-year health law delay in a stopgap spending bill. By Saturday, House Speaker John Boehner, R-Ohio, had adopted a similar approach.

Senate Majority Leader Harry Reid, D-Nev., called the gambit “pointless” and promised to vote it down. The Senate is due back Monday, though it could choose to return Sunday.

On Friday, the Senate passed a bill to fund the government at existing spending levels through Nov. 15.

The House was set to amend the Senate bill to include a one-year delay of the parts of the health law that are not yet implemented and repeal the law’s 2.3 percent tax on medical devices, while extending funding to Dec. 15.

In addition, the House was to approve a separate measure to pay military members if there is a shutdown. Without that bill, military paychecks could be delayed.

House leaders revealed the plan Saturday afternoon to a cheering GOP caucus.

“There’s a lot of smiles coming out of that room, a lot of thumbs-up,” said Tifton Republican Rep. Austin Scott.

They did not discuss contingency plans if the Senate does not agree, nor did they propose a one-week spending bill to buy more time for negotiations. Then again, there appear to be no negotiations at all among the House Republicans, Senate Democrats and the White House, just a high-stakes game of legislative pingpong.

“That’s just going to postpone the inevitable,” Coweta County Republican Rep. Lynn Westmoreland said of a one-week bill.

Republicans believe their plan offers difficult votes that could sway moderate Senate Democrats. They said the same thing about their proposal last week to permanently strip funding from the law, but all Senate Democrats united to return serve with a bill that funded the health law.

Multiple House Republicans pointed to comments last week from Sen. Joe Manchin, D-W.Va., who said he wants to delay the requirement that all individuals purchase health insurance.

“All we’re suggesting is a bipartisan solution for this,” said Rep. Phil Gingrey, a Marietta Republican who is running for U.S. Senate next year.

But Manchin also said, “I do not believe that this issue should be used to shut down the government, and I will not vote to shut down the government.”

In addition, many Senate Democrats have supported repealing the $30 billion tax on medical devices, as a nonbinding vote this year to do so passed 79-20.

But Reid insisted Saturday that Democrats would still reject it as a precondition for keeping the government open.

“We continue to be willing to debate these issues in a calm and rational atmosphere,” Reid said in a prepared statement. “But the American people will not be extorted by tea party anarchists.”

The White House vowed a veto, as press secretary Jay Carney said, “Any member of the Republican Party who votes for this bill is voting for a shutdown.”

Republicans roll their eyes at such statements, insisting the onus is on moderate Democrats to vote to keep the government open and pull apart the divisive Affordable Care Act.

“The stakes are high enough and the visibility is high enough that it’s not a gimme for senators anymore,” said Rep. Jack Kingston, a Savannah Republican who is running for U.S. Senate next year.

“And you know in the past they could just say, ‘Oh, what the hell.’ But I think at this point in America everybody knows Obamacare does not decrease the cost of medicine and it does not increase the access, and those are two of the main objectives.”

Enrollment begins Tuesday on state-based health insurance exchanges, coinciding with the shutdown deadline. But the law would be largely unimpeded in a shutdown, as most of the funding is already in place or is considered “mandatory” and not subject to stopgap spending fights. Other mandatory payments such as Social Security checks, Medicare reimbursements and food stamps would continue to flow as well in a shutdown.

Momentum has been building since August, fueled by conservative pressure groups such as Heritage Action for America, to make the shutdown the last stand against the health law. Graves and Sen. Ted Cruz, R-Texas, led the charge in their respective chambers.

Cruz made enemies in his own party by attacking Republicans amid tactical disagreements, while Graves took a more congenial approach in rallying a larger group of House arch-conservatives who are more amenable to brinkmanship over the health law than their Senate counterparts. After leaders acquiesced to his strategies, the entire House GOP hopped on board.

“I’ve always approached things as, how can we find the common denominators?” Graves said.

That common ground does not include House Democrats.

Rep. John Lewis, an Atlanta Democrat, said he would only vote for a spending bill that doesn’t touch the health law, and he predicted a shutdown.

“It’s a stalemate,” he said.