MT. LEBANON, Pa. — A special election for a U.S. House seat was too close to call late Tuesday as Democrat Conor Lamb and Republican Rick Saccone were separated by several hundred votes in a race that had become a test of President Trump’s political clout.

With several thousand absentee and provisional ballots outstanding, Lamb earned 49.9 percent of votes cast and Saccone earned 49.5 percent, with 99.7 percent of precincts reporting. A recount is possible if the candidates are separated by 0.5 percentage points or less.

Hours after supporters at respective campaign events waited for some finality, Saccone told his backers, “You know we’re still fighting the fight. It’s not over yet.”

At Lamb’s party, exhausted supporters groaned when told to keep waiting for more ballots to be counted. However, the Democratic Congressional Campaign Committee declared victory for Lamb, confident that the absentee ballots would not erase his lead.

Lamb, 33, had waged an energetic campaign in the district that Trump carried by nearly 20 points in 2016 but that opened up after the Republican incumbent was felled by scandal. Republicans cited that scandal, along with the lackluster campaign of their nominee, Rick Saccone, to minimize the closeness of the race. The district itself will disappear this year, thanks to a court decision that struck down a Republican-drawn map.

Democrat Lamb and Republican Saccone are competing in Pennsylvania’s 18th District.

But led by the White House, Republicans had elevated the race to a high-stakes referendum on the president and the GOP. Trump made two appearances with Saccone, including a Saturday-night rally in the district, and his son Donald Trump Jr. stumped with the Republican on Monday. The president repeatedly linked his brand to Saccone.

“The Economy is raging, at an all time high, and is set to get even better,” the president tweeted on Tuesday morning. “Jobs and wages up. Vote for Rick Saccone and keep it going!”

Republican campaign committees and super PACs spent $10.7 million to help Saccone, more than five times as much as their Democratic rivals, according to Federal Election Commission records filed Monday night.

Thanks to the court’s scrambling of the congressional map, both Lamb and Saccone may well become candidates in new districts before a winner is declared in the 18th Congressional District. Candidates must collect and file 1,000 signatures for those races by March 20 — the day that some overseas ballots in Tuesday’s race will be counted.

The district, a stretch of suburbs and small towns that was drawn to elect a Republican, was not the sort of place that Democrats had been expected to make competitive this year. Lamb’s coalition pulled together suburban liberals, wayward Republicans and traditional Democrats who had drifted from the party on cultural issues.

The tight race added to Republican woes on a day that began with the surprise firing of Secretary of State Rex Tillerson and a string of related dismissals. Republicans who hoped to fight the Pennsylvania race on the growing economy, and on the president’s new tariffs on foreign steel and aluminum, found the White House frequently alienating some of the voters they needed.

As voters made their decisions Tuesday, Trump loomed large in the minds of many.

Amelia Fletcher, a registered independent from Moon Township, cast her first-ever ballot for Saccone because she likes Trump’s…