Is it just me, or does Mick Mulvaney look a bit tense lately?

You could hardly blame the guy. The Great Republican Health Care Meltdown has been rough on the White House budget director, who was a central player in President Trump’s push to save the GOP’s floundering plan. But as the House vote approached, Mulvaney found himself increasingly at odds with a chunk of the conservative Freedom Caucus. Which is ironic, given that he co-founded the group and, until joining the administration, was a devout member.  

While no one much liked the AHCA (How about that 17 percent approval rating!), Freedom Caucusers were particularly put off by what many considered “Obamacare lite.” The more they dug in, the huffier Trump got. He started calling out caucus members in closed meetings and through his pet negotiating tool, Twitter.

Finally, last Thursday, Trump sent a vote-tomorrow-or-else ultimatum to the Hill via Mulvaney. In a vaguely sour appearance on CNBC the next morning, Mulvaney insisted the message was for all House Republicans, not any specific group. Still, everyone knew that his Freedom Caucus chums were among Trump’s chief marks. And Mulvaney himself scolded his old friends for sacrificing the good to the perfect.

Mulvaney got even rougher with the caucus after leadership axed the vote. On NBC’s Meet The Press Sunday, Chuck Todd grilled the budget chief about why he had been unable to get Freedom Caucusers to “yes.” Mulvaney rambled on about how Washington is more “broken” and “rotten” than even he had imagined. “I know the Freedom Caucus. I helped found it. I never thought it would come to this,” he lamented. He characterized the AHCA’s demise as another sad case of “the powers that be in Washington” crushing action-oriented reformers. Rejecting Todd’s suggestion that the bill was fatally flawed, Mulvaney trashed opponents’ motives. “They're still paying attention to special interests, they're still paying attention to getting reelected, as opposed to doing the right thing.”

Say this for the budget chief: It took impressive shamelessness to throw this kind of shade at former colleagues, seeing as how Mulvaney spent his own House career perfecting exactly the sort of intransigence, disruption, and ideological piety he’s now grumping about. When it came to giving the finger to legislative pragmatism, compromise, and “good enough,” no one beat Congressman Mulvaney.

And now? After less than two months in the executive branch, Mulvaney appears to have had an epiphany about the art of the possible, the limits of ideological purity, and the vast difference between governing and blowing stuff up. At the very least, he’s learned how it feels to carry someone else’s water. For the past couple of weeks, in fact, the one-time bomb-throwing zealot has sounded suspiciously like one of those deal-cutting RINO squishes he used to lived to torment. (Neither he nor members of the Freedom Caucus wished to comment.)

Worse, the health care crackup promises to be only the first of many awkward situations barreling his way. In the coming months, Mulvaney will frequently be headed back to the Hill to discuss delicate issues such as tax reform and “continuing resolutions ” and “skinny budgets” and spending caps. Like many House Republicans, he is a fierce budget hawk—one who repeatedly voiced his preference for shutting down the government in the service of taming spending.

His new boss, by contrast, has bragged about being “the king of debt” and, since taking office, has been floating all sorts of tax cuts and spending plans—including a $1 trillion infrastructure package—that would blow a fat hole in the budget. (It bears mentioning that the continuing resolution, or CR, currently funding the government expires in late April, opening the door for potentially spicy funding squabbles.)

Aspects of tax reform that interest Trump, such as some version of a border tax, do not sit well with many fiscally conservative lawmakers. Nothing in the president’s skinny budget would significantly shrink deficits. (He is looking to jack up Pentagon spending by $54 billion, requiring commensurate slashing of non-defense spending just to break even.) Dramatically complicating the math, Trump has vowed not to touch entitlements, the overhaul of which Mulvaney and many of his former colleagues see as necessary to the nation’s fiscal health.  

Then there’s the debt ceiling. As even casual observers of congressional dysfunction can tell you, lawmakers’ treating America’s debt obligation as a political football is among the more unnerving developments of recent years. (In 2011, such brinkmanship led to the first ever downgrading of the U.S.’s credit rating.) Mulvaney has consistently been among the most enthusiastic proponents of this trend, dealing congressional leadership fits whenever the issue arose.

Technically, Congress blew through the deadline for raising the debt ceiling earlier this month. Treasury Secretary Steven Mnuchin notified House and Senate leaders that he would begin “extraordinary measures” to avoid default and keep the government running. But that will only kick the can so far, meaning that later this year, Congress must raise the ceiling or risk setting off an ugly chain of events.

Mnuchin firmly opposes dorking around with the nation’s fiscal obligations. As he noted at an event hosted by Axios last week, “We’ve spent the money, so the concept of the debt limit is somewhat of a ridiculous concept.” Urging Congress to tackle the issue before summer break, he said, “I think everybody understands, whether you’re a Republican or a Democrat, we need to raise the debt limit, and that’s something we’re going to do. And that the full faith and credit of the United State is the most important thing.”

Well, not everybody understands that. In 2010, Mulvaney dismissed the very notion that failing to raise the debt ceiling was a bad thing: “I have yet to meet someone who can articulate the negative consequences.” And many of his Freedom Caucus brethren are expected to try to use the debt limit as a bargaining chip again.

This could soon present Mulvaney with the ultimate political irony. In the past, Trump has tweet-slammed Congress for raising the debt ceiling. But that was pre-White House, when could twiddle his thumbs with impunity. Now, if his party tanks America’s credit rating and/or shuts down the government, Trump will share the blame. As such, come Fall, there is an excellent chance that the president will send Mulvaney, hat in hand, to ask Congress to raise the ceiling.

Republican members who clashed with Congressman Mulvaney on the debt issue, or others like it, could be excused for feeling a tremor of schadenfreude at this turn of events. His former Freedom Caucus colleagues, meanwhile, will need to learn not to take this kind of thing to heart. Mulvaney no longer has the luxury of being a damn-the-torpedoes rabble-rouser. In Trump world, he’s looked upon as a relatively seasoned political grownup. This inevitably comes with way more responsibility, and is typically a heck of a lot less fun.