THE CANDIDATES — A cameraman takes footage of the signs for the two candidates outside a polling place in the special election being held for the PA 18th Congressional District vacated by Republican Tim Murphy, Tuesday in McKeesport, Pa. Republican Rick Saccone had just voted at the site. Saccone was opposed by Democrat Conor Lamb. -- Associated Press

MT. LEBANON, Pa. (AP) — A razor’s edge separated Democrat Conor Lamb and Republican Rick Saccone early today in their closely watched special election in Pennsylvania, where a surprisingly strong bid by first-time candidate Lamb severely tested Donald Trump’s sway in a GOP stronghold.

Lamb claimed victory before supporters after midnight, though many absentee ballots were still to be counted in the contest that has drawn national attention as a bellwether for the midterm elections in November when the Republican Party’s House and Senate majorities are at risk.

Lamb, a Marine veteran, told his crowd that voters had directed him to “do your job” in Washington. “Mission accepted,” he declared. Earlier, Saccone told his own supporters, “It’s not over yet, we’re going to fight all the way, all the way to the end, we’ll never give up.”

Regardless of the outcome — and a recount was possible — Lamb’s showing in a district Trump won by 20 points in the presidential race was sure to stoke anxiety among Republicans nationwide and renewed enthusiasm among Democrats.

After midnight with all precincts reporting, unofficial results had Lamb leading Republican state Rep. Saccone by fewer than 600 votes. More than 1,000 absentee ballots were still being tabulated as the count carried into today.

In a race this close, either candidate’s supporters can ask for a recount. However there are stiff requirements, including requiring three voters in the same precinct who can attest that error or fraud was committed.

The stakes in the high-profile special election were more political than practical.

The ultimate winner will face re-election in just eight months, and the congressional district as currently shaped will likely vanish next year thanks to a court-ordered redrawing of the state’s district maps. Yet President Trump and his chief allies invested tremendous time and resources in keeping the seat in Republican hands, mindful the contest could be used to measure Trump’s lasting appeal among white, working-class voters and Democrats’ anti-Trump fervor.

The White House scrambled to rally voters behind Saccone, who cast himself as the president’s “wingman,” but he struggled at times to connect with the blue-collar coalition that fueled Trump’s victory little more than a year ago.

Lamb, a 33-year old former federal prosecutor, asserted his independence from the Democratic Party, courted labor backing and focused on local issues. He studiously downplayed his opposition to the Republican president in the district where Trump’s support has slipped but not plummeted.

“This didn’t have much to do with President Trump,” Lamb said Tuesday after casting his vote in suburban Pittsburgh.