MT. LEBANON, PA. — Working-class voters across western Pennsylvania on Tuesday are weighing in on a surprisingly tight congressional contest that has pit strength of President Donald Trump's grasp on blue-collar America against the energy and anger of the political left.



The fight between Republican state Rep. Rick Saccone and Democrat Conor Lamb has drawn national attention as a bellwether for the midterm election in November.



In a region President Donald Trump carried by 20 points, the White House has scrambled to rally voters behind Saccone, who cast himself as the president's "wingman," but has struggled at times to connect with the blue-collar coalition that fueled Trump's victory little more than a year ago.



Democrat Conor Lamb, a 33-year old Marine veteran and former federal prosecutor, downplayed his opposition to the Republican president on Tuesday and insisted instead that the race hinged on local issues.



"This didn't have much to do with President Trump," Lamb said after casting his vote in suburban Pittsburgh.



Polls close at 8 p.m.



Tuesday's winner will face a re-election test in just eight months and a redistricting battle all-but ensures the district is likely to be redrawn by then. Despite the short-term stakes on Capitol Hill, the election has far greater political consequences as each party prepares for the November midterm elections.



For the White House and its Republican allies, a Tuesday loss would represent both a profound embarrassment and major cause for concern in the broader push to defend its House and Senate majorities.



The president has campaigned in the district twice and sent several tweets on Saccone's behalf. Other recent visitors include the vice president, the president's eldest son, the president's daughter and the president's chief counselor. Outside groups aligned with Republicans have also poured millions of dollars into the contest.



For Democrats, a win would reverberate nationwide, while even a narrow loss would be viewed as a sign of increased Democratic enthusiasm just as the midterm season begins.



Democratic voter Brian Konick supported Trump in 2016. On Tuesday he voted for Lamb.



"He's a little more my style, a little more moderate," Konick, a 51-year-old Jefferson Hills resident, said of the Democratic candidate.



Registered Republican Brett Gelb voted for Saccone, largely because the Republican candidate promised to support the president.



"Saccone backs a lot of President Trump's plans for the country," said Gelb, a 48-year-old fire technician who lives in Mt. Lebanon. He added, "I do think Trump is doing a good job. I think he needs backup."



Democrats must flip 24 GOP-held seats this fall to seize control of the House, and few counted on this Pittsburgh-area district to be in play. The seat has been in Republican hands for the last 15 years.



It's open now only because longtime Republican congressman Tim Murphy, who espoused strong anti-abortion views, resigned last fall amid revelations of an extramarital affair in which he urged his mistress to get an abortion.



After voting Tuesday in Allegheny County, Saccone downplayed the significance of the unusually close race.



"The Democrats ... they're throwing everything they can at this race," he said. "There hasn't been an open seat for a long time."



Besides bruising the president, a Lamb defeat also could shake Republican self-assurance that their new tax law can shield them from other political woes.



With polls showing a tight race for months, Saccone has implored the GOP-leaning electorate that their choice is about "making America great again," just as the president says.



The 60-year-old Air Force veteran turned state lawmaker and college instructor enjoys enthusiastic backing from social conservatives who've anchored his state career, and he's perhaps at his most animated when he touts his opposition to abortion rights.



Yet Saccone struggled to raise money and stir the same passions that helped Trump sweep the industrial Midwest on his way to the White House. The consistent fundraising deficit has left him with limited resources to air the message he delivers one-on-one: His four decades of experience in the private sector, international business and now the legislature make voters' choice a no-brainer.



Lamb, meanwhile, has excited core Democrats and aimed for independents and moderate Republicans.



"We worked really hard for it," Lamb said after voting.



He did it as national Republican groups filled airwaves and social media with depictions of the first-time candidate as little more than a lemming for Nancy Pelosi — the California Democrat, House minority leader.



Lamb answered the critique by saying he won't support Pelosi as floor leader, much less a return to the speaker's rostrum. He also says he opposes major new gun restrictions — though he backs expanded background checks — and declared himself personally opposed to abortion, despite his support for its legality.



Lamb has largely avoided mentioning Trump, who remains generally popular in the district even if slightly diminished from his 2016 dominance.



He pairs those tacks with Democratic Party orthodoxy on the new GOP tax law, hammering it as a giveaway to corporations at the certain future expense of Social Security, Medicare and the nation's fiscal security. And he embraces unions, highlighting Saccone's anti-labor record at the statehouse — a noticeable deviation from Murphy's status as a union-friendly Republican.



The AFL-CIO counts 87,000 votes from union households — around a fifth of the electorate.



In a final-hours message on Fox Business Network, Saccone said that he's ready and willing to help Trump.



"He's getting beat up in Washington as you see, from the media, from the bureaucracy and from Hollywood," Saccone said. "He needs a good wingman."