Rep. Tom MacArthur (R-N.J.) is interviewed outside the House chamber after House Republicans voted to pass his version of their health-care revision bill. (Eric Thayer/Getty Images)

The congressman who almost single-handedly revived Republicans' health-care bill has now resigned from his leadership post for reviving it.

If that doesn't underscore just how politically volatile Republicans' attempts to change Obamacare is … well, it should.

On Tuesday, Rep. Tom MacArthur (R-N.J.) told members of the 50-ish center-right lawmakers that call themselves the Tuesday Group that he is resigning as one of the group's co-chairs.

(Not a coincidence his resignation came on Tuesday; the decades-old group was named for the day they would meet in the Capitol basement.)

MacArthur said the majority of today's Tuesday Group just couldn't make peace with how he revived Republicans' health-care bill in a way that got conservatives on board and ultimately got it passed in a seemingly hopelessly divided House Republican caucus.

The bill's passage doesn't seem to have unified Republicans. Since MacArthur has made himself the face of Republicans' health-care overhaul, he's paid a price for it from nearly every angle — Democrats, members of his own party, members of his own wing of his party.

“You can't lead people where they don't want to go,” MacArthur told Politico's New Jersey edition, which first reported the news. “I think some people in the group just have a different view of what governing is.”

To better understand what he means by this, let's rewind to March, when Republicans failed to get enough votes for their first version of the health-care bill and had to cancel a high-profile vote.

At the time, Republicans were basically openly admitting they were ungovernable.

“Moving from an opposition party to a governing party comes with growing pains,” said House Speaker Paul D. Ryan (R-Wis.), who knows a little something about taking the blame for health care: After Republicans pulled this bill, Fox News host Jeanine Pirro said Ryan should resign — just before Trump tweeted his followers should watch her show.

Congress went on break, and when it came back, MacArthur had an idea: Why not let the states opt out of Obamacare regulations, like expanding Medicaid and covering preexisting conditions and other benefits Obamacare said insurers had to cover?

The moderate leader got support from key conservatives. The new provision of the bill became known as the MacArthur Amendment. Suddenly, Republicans' attempts to roll back Obamacare was alive again.

More than 30 lawmakers who didn't support the first bill switched to “yes” on the MacArthur-tweaked version, including more than a dozen conservatives. Two months after being embarrassed and humbled, Republicans were victorious. Kind of. They managed to heave the new version of the bill to passage by a couple votes. House Republicans celebrated with President Trump in the Rose Garden.

President Trump gathers with congressional Republicans in the Rose Garden of the White House after the House of Representatives approved the American Healthcare Act on May 4. (Carlos Barria/AP)

Since then, there has been little for MacArthur and the bill's backers to celebrate. The Senate basically tossed the bill the House sent them in the trash can. Key pieces of it won't survive a Senate Democratic filibuster, and other portions — like allowing some insurers to jack up the rates on people with preexisting conditions — were toxic non-starters for the Senate anyway.

But the House version didn't just disappear. MacArthur visited a liberal enclave in his swing New Jersey district a week after the vote and spent five hours defending himself to 200 irate constituents.

Protesters demonstrated outside of a town hall hosted by Rep. Tom MacArthur (R-N.J.) on May 10 after he voted to pass the GOP health-care bill. (Twitter/@brianbaumley)

“I hear people calling me an idiot. I hear people shouting curse words,” an exasperated MacArthur finally said. “I wonder, I really wonder how any of you would perform in Congress with that attitude.”

Democrats have ramped up their efforts to get a strong Democratic candidate to challenge MacArthur, who was already on their target list.

Back in Congress, more moderate members let MacArthur know how much they hated his work.

“You are going to make us lose the majority,” one lawmaker told him, as MacArthur relayed to Politico a day before the vote.

Things could get worse for MacArthur still. On Wednesday, the Congressional Budget Office will offer its nonpartisan estimate of how many people could lose health insurance on this new version of the bill and how much it will cost the government. If it's anything like the last score, it will give Republicans who hate this health-care bill even more heart burn.

The ultimate irony is that all of the heat MacArthur's taken could be for nothing: The bill that Senate Republicans write and try to pass could be very different from the bill House Republicans passed. To get anything to Trump's desk, the two chambers will have to find a compromise, and it's not likely a compromise will be as far right as MacArthur's compromise with House conservatives was.

If MacArthur's story tells us anything, it's that health care is hard, and the Republican Party is far from unified on it.