It only took a week for Pennsylvania Rep. Ryan Costello, a moderate Republican representing suburban Philadelphia, to recognize the headwinds that Donald Trump’s presidency would create for him and members in similar districts.

“After the travel ban,” Costello said in an interview Tuesday. It wasn’t just the overwhelming protests at airports but all the protesters who gathered at his office, too. They were linking him, their Republican member of Congress, with the decisions of the new Republican president. He remembered “the expectation that, somehow, I needed to issue a statement within X number of minutes or somehow I was complicit, or whatever they were trying to accuse me of.”

“And what that told me,” he continued, “is that they were very engaged, and there was a lot of anger, and they were just waiting for Trump to do something so that they could express their outrage.”

Costello, a 41-year-old serving in only his second term, announced over the weekend that he will not run for re-election. What would have been a challenging race became near-impossible when the Pennsylvania Supreme Court redrew the state’s congressional lines, turning the state’s 6th Congressional District from an R+2 to a D+2 seat, and one that Hillary Clinton would have won by 10 percentage points in the 2016 election. Costello has called for the Pennsylvania judges behind the new map to be impeached.

Costello has explained his frustration with the congressional maps. I was more interested to hear a newly liberated Republican member of Congress, if we can call him that, talk about what it’s been like the last 15 turbulent months.

He gamely rattled off some of the difficult events from the past year: “Charlottesville. Firing of Comey. Then there’s been a couple of tweets. The Mika Brzezinski tweet was something. Didn’t he say Kirsten Gillibrand would do anything for money?” (He did.)

“Things like that were little bumps in the road,” he said. “It was stormy before there was Stormy.”

I asked him how Republican members in swing districts thread the needle when the president makes one of these remarks.

“There’s no threading the needle,” Costello said. “The more people think you’re trying to thread the needle, the more they’re actually going to be critical.”

Anytime he spoke out against one of the president’s comments, he knew exactly where the responses would fall: It would never be enough for Democrats and other truly anti-Trump constituents, but it might pass muster with the persuadable Republican or independents he needed to keep on board. “And when you do that, you need to be prepared for the really pro-Trump Republicans to come at you for not sticking up or defending the president.

“It’s a zero-sum calculation,” he said.

He emphasized throughout the interview that he had no complaints about the way he’s been treated by partisans on either end of the spectrum. “You’re fair game as an elected official,” he said. And though many members complain endlessly about reporters bugging them with questions about the latest Trump tweet, Costello understood why constituents would want to hear an on-the-record response from their representative in Washington. He didn’t enjoy the process, but he became more comfortable with it as time went on. He could give reporters his statement on whatever Trump had said, and then try to move on to discussing whatever policy he was working on.

Costello described the health care fight as the most “intense” experience of his brief political career, “period.” He remembered being one of the 15 or so members who would decide the fate of the House GOP health care bill and “getting it from all angles.” (He voted against it.) When you’re serving in a swing district in this environment, he said, “you have to know every single issue, and why you’re voting the way that you are, and to be able to explain it. Because you will get asked about it by everyone.”

“The way that these bots work”—“B-O-T-S,” he spelled it out to me, presumably referring to those deluging him with talking points—“and these Indivisible people, it’s not like they think for themself, they’re just told what to say,” he said. “They’ll take what some other expert told them to say, like Topher Spiro, or whatever that guy’s name is.” That is indeed the name of the excitable Center for American Progress policy fellow who built up quite the Twitter presence during the health care fight by imploring his followers to flood congressional phone lines.

“It’s not as though the criticisms or questions are illegitimate, but you are on the spot for answering them,” Costello said. “And so you have to be very well-prepared, and you just have to accept that no matter what you say, it’s not going to be good enough, the next criticism’s going to come at you. Which is fine.”

When you’re a Republican member of Congress, he said, all of the anger that anti-Trump voters feel toward the president is “directed at you.” You are the front lines facing those with whom Trump has never, and will never, personally interact. And though he believes that tax bill will still serve as a “net positive” for members in competitive districts—and he thinks that if any president besides Trump had signed that bill, it would have been much more popular—the tax bill alone will not save members from the anti-Trump energy. You have to “differentiate” yourself from the president on some issues.

“People in any district, but especially in [suburban] districts, they want to know that their member of Congress is looking out for them, not for any particular party,” he said. “It could be trying to get EPA funding for the remediation site, it could be a public transportation project.

It could be forcefully fighting for DACA, or pushing back against getting out of the Paris accord. Or trying to stabilize the health insurance marketplace.”

The last of those items, stabilizing individual health insurance markets, was something Costello had worked on last week. The bill that he co-authored with Sens. Lamar Alexander and Susan Collins, as well as Rep. Greg Walden, didn’t make it into the omnibus spending package as talks between Democrats and Republicans fell apart, largely over abortion politics. I asked him if that experience soured him on Congress and contributed to his decision to leave.

Not at all, he said.

“I wish more of my days were spent at press conferences talking about” health care policy, he said, “rather than talking about Stormy Daniels or whatever Trump said or tweeted. It’s the latter stuff that just wears on you.”