In any case, by infuriating state Republicans, Costello has probably ensured that he'll never have their support if he ever chooses to run for office again. It's a surprising end for a guy who was viewed by both parties just a few months ago as a very formidable candidate and had always been well-regarded by the GOP. Indeed, when Republican Rep. Jim Gerlach unexpectedly decided to retire in 2014, the party very quickly consolidated behind Costello, who was chair of the Chester County Board of Commissioners at the time.

Costello proved himself a strong fundraiser in that race, and he honed a moderate image that played well in this competitive district. While Team Blue hoped to target the seat with Gerlach leaving, D.C. Democrats weren't happy when physician Manan Trivedi, who’d been the party’s nominee in both 2010 and 2012, won the primary again. Major Democratic outside groups canceled their ad reservations in October to focus on more competitive races, and Costello won 56-44.

Democrats had no more luck against him the next cycle. National Democrats were initially pleased when they landed businessman Mike Parrish, whom they had wanted as their nominee back in 2014, but his fundraising was awful. Outside groups once again focused their attention on other races, and Costello won 57-43. Houlahan stepped up early to challenge congressman in 2017, but it seemed like the well-funded incumbent with the right profile for his seat was still favored to win again. NRCC chair Steve Stivers even issued a dare of sorts, calling Costello a “bellwether” and saying that if Democrats could beat him—something he obviously didn’t believe would happen—“they’ve got a shot to take the majority.”

However, there were signs that Costello wasn't ready for a serious challenge even before redistricting altered his seat. Back in January, he accused two "associates" of Houlahan of trespassing on his property to take photos of his home and "intimidate" his wife. Not so, said the police, who investigated the matter and determined there had been "no crime committed." Apparently, two Planned Parenthood canvassers had come to his house and left when his wife asked them to. But when a reporter explained this to Costello, he replied, "I think that just makes it all the more weird and creepy, to be honest with you."

The weird behavior was Costello’s, but that was nothing compared to how he reacted when the Pennsylvania Supreme Court invalidated his gerrymandered district, along with the rest of the state’s congressional map. Even though the 6th became bluer, there was still plenty of reason to think Costello could win again, if he was in fact the strong, “moderate” candidate he was reputed to be: Republican Sen. Pat Toomey narrowly carried the new 6th during his 2016 re-election campaign, and the GOP has traditionally done well in this area down the ballot,

But Costello instead decided to throw a tantrum, calling the new lines "1,000 percent partisan," a Democratic gerrymander in "disguise," and even "racist"—the first time, it seems, Costello ever showed any concern for minority voting rights. Pitching his “moderate” image right out the window, Costello then joined in with other Pennsylvania Republicans in thuggishly calling for the impeachment of the Supreme Court justices who ordered the state to adopt its new map.

And while Costello could have done his party a small favor and just retired then and there to give Republicans time to find another contender, he went about filing his petitions to get on the ballot while refusing to say if he was running again. Costello ended up announcing his retirement only after the filing deadline, which is how we’ve arrived at this point.

There's a lesson to be learned from the brief career of Ryan Costello. There are plenty of incumbents in the House who hold competitive seats but seem so formidable that they almost never attract a credible opponent. Sometimes, these incumbents actually do live up to their reputation and run strong campaigns in tough election years and win. But often, you get people like Costello, who have the good fortune run their first races in wave elections and only show their true colors when they're finally in trouble.

Costello is an unusual case, since the district that he won so easily in no longer exists. However, he's still a good reminder of why it's always essential to run strong candidates even against seemingly tough opponents, because sometimes, those opponents turn out not be so tough after all.