WASHINGTON — A trio of GOP senators challenged their colleagues — especially Republicans — to join an effort to block funding for Obamacare in the continuing resolution that’s expected to keep the government running in the usual absence of a budget come Sept. 30.

“We don’t have to vote to fund something with which we fundamentally disagree,” said Sen. Mike Lee (R-Utah), who led the afternoon colloquy on the floor of the upper chamber. “…Defund it or own it — if you fund it, you’re for it.”

But Sen. Tom Coburn (R-Okla.), touting his credentials as an original opponent of the 2010 law, wielded a new Congressional Research Service report that states Obamacare can’t be defunded by stemming the appropriations process — leaving repeal, which has never made it through the Senate, the only option.

Coburn took issue with Sen. Ted Cruz (R-Texas) for saying that Congress is to blame for the law.

“I would just say thank the Democrats, because not one Republican voted for it,” the Oklahoma senator said. “…The president and his allies created this mess that we’re about to deal with.”

The report released by Coburn’s office today says “substantial implementation might continue during a lapse in annual appropriations that resulted in a temporary government shutdown.”

“You cannot design a piece of legislation to defund Obamacare because the vast majority of it is mandatory spending,” Coburn told his colleagues, adding “their motivations are absolutely pure” and stressing that he’s never voted for a continuing resolution out of opposition to the stopgap measure in principle.

“The only effective way to truly stop Obamacare … would be to totally reverse it,” he added. “We don’t have the votes to do that. But we do have the votes to delay it.”

Cruz admitted in the colloquy that the votes weren’t currently there to pass a wholesale defunding of Obamacare, but said Republicans and some Democrats could come around if the American people rose up “en masse” over the next 62 days to demand a freeze to the healthcare law.

“Nothing is hurting the American economy more than Obamacare,” Cruz said. “There is bipartisan agreement on that.”

Cruz said the 190 million hours or more of Obamacare paperwork burdens expected every year  were enough for Mount Rushmore to “be constructed 1,547 times.”

The show of force by Lee, Cruz and Sen. Marco Rubio (R-Fla.) just before the August recess stirred reminders of the 2010 congressional recess, where town hall meetings seethed with anger over Obamacare, signed into law that March, and a budding Tea Party movement took the House out of Democrats’ hands in midterm elections.

It was also the year Lee and Rubio won their seats.

Rubio compared Obamacare to New Coke, a 1985 reformulation of the classic cola that was so reviled the company shifted back to Coke Classic.

“What did Coca-Cola do when New Coke began to flounder? They didn’t say, ‘Well, we’re just gonna continue to make more of it.’ They backed away from it. They went back to the original formula. They learned from their mistake, and they didn’t double down. That’s the way it is in the real world,” Rubio said. “That’s the way it is in our lives, and that’s the way it is in the private sector, but not government. Not Washington!”

He said that he’ll vote for every repeal bill, but called the chance of any such legislative effort working “minimal as long as President Obama is president of the United States.”

Rubio argued that if a continuing resolution defunding Obamacare passed, and Obama refused to sign it, then a government shutdown would be on his hands, not the Senate’s.

“To my colleagues in Republican Party — this is our last best chance to do something about this,” he implored. “…You cannot go home and say you did everything you did to stop Obamacare if you vote for a budget that funds it.”

Lee noted the array of uncertainty and premium hikes already being realized in the law’s early days, adding that the Affordable Care Act is a “misnomer.”

“We don’t know exactly how much healthcare is going to cost us,” he said, noting that the bill still has yet “to be modified by tens of thousands of pages of regulations.”