Pennsylvania’s 18th Congressional District, which ripples over the steep hills of this Pittsburgh suburb and stretches south to the West Virginia border, has not had a competitive congressional election since 2006. The fact that it will have one on March 13 makes this the most important 2018 voting before Nov. 6.

The seat’s most recent occupant, Republican Tim Murphy, 65, a married father, had won it eight times, the last two times unopposed, and by 28 percentage points when last opposed, in 2012. A fervent anti-abortion social conservative, he resigned in 2017 amid some ethical challenges, including allegations that he urged his pregnant girlfriend to get an abortion. The national GOP under its current livewire leader, Stormy Daniels’ acquaintance, is decreasingly convincing as a vessel of social conservatism, but at least it still opposes deficit spending and protectionism.

Democrats retain an approximately 70,000 registration advantage in this district, a residue of its past as home to unionized steelworkers (there are 86,000 union households). It was, however, voting Republican in federal elections long before the president discovered that he is a Republican. It has voted Republican in five consecutive presidential elections; in those, George W. Bush (twice), John McCain, Mitt Romney and Donald Trump carried it with 49.7, 53.3, 55.2, 57.9 and 58.1 percent, respectively. There was no surge for Trump, just the continuation of a trend.

The Republican nominee to hold the seat, Rick Saccone, a 60-year-old four-term state legislator, says he was “Trump before Trump was Trump,” which is probably true but might not be saying much, the eponymous fellow having recently arrived at his current convictions and party allegiance. Saccone has lived an eventful life: 18 years in the Air Force, a Ph.D. in international relations, author of nine books, two of them on North Korea, where he lived for a year negotiating nuclear policy. His Democratic opponent is Nancy Pelosi.

Actually, it just seems that way. One ad run on his behalf warns that his actual opponent, Conor Lamb, would be — wait for it — “one of Nancy Pelosi’s sheep.” Lamb immunized himself early on by saying that if Democrats win a House majority, he will not vote for Pelosi as speaker. Seasoned professional that she is, she probably is bemused that her hopes of becoming speaker depend on some Democratic House candidates pledging to oppose this.

If Democrats had asked a Hollywood studio to supply a candidate for this time and place, it would have sent Lamb. He is 33, 6 foot 3, the nephew of Pittsburgh’s controller and the grandson of a former majority leader of the state Senate. He has the polish of a former Marine officer and federal prosecutor, and radiates a determination not to radiate anything other than placidity. He says that the biggest surprise of the campaign has come when knocking on doors: “I thought there would be more about specific issues.” Instead, people just want compromises, by which they mean calm.

The first day of deer-hunting season — Nov. 26 this year — is a school holiday in many communities in Pennsylvania, and after the Florida school shooting, Lamb said something true and therefore discordant with national Democratic pronouncements: “There’s not one thing we can do with the stroke of a pen or one thing you can ban” to prevent such tragedies. Lamb says that many local offices in the district are held by Democrats, and that Democratic voters are energized by the novelty of a competitive race.

Pennsylvania has the nation’s fourth-oldest residents, and this district is the second oldest. Here retirees are worried about soaring health care premiums and rickety union pension funds. Polls show Saccone with a single-digit lead in a tightening race, and Trump’s approval and disapproval almost even.

Recently, Democrats won a Wisconsin state Senate seat in a district Republicans had held since 2001 and that Trump carried with 55 percent of the vote. And a Republican-held Kentucky state legislative seat in a district Trump won with 72 percent. Last Tuesday, Democrats captured a Connecticut House district that Republicans had held for 44 years, and a New Hampshire district Trump won by 12 points. Southwest Pennsylvania, as much as any place in the nation, made Trump president. He, his daughter and his vice president have campaigned for Saccone, on whose behalf the spending advantage has been estimated to be 17 to 1. If Lamb nevertheless wins, Democrats will have found a template for many districts in 2018: candidates who seem ideologically unlike the national party and temperamentally unlike the president.

© 2018, Washington Post Writers Group