President Donald Trump on Thursday pledged “total support” for a Pennsylvania lawmaker trying to keep a House seat in Republican hands in the first congressional race of the year, tweeting his endorsement hours before visiting the state.However, the White House later corrected Trump’s tweet to say the president was traveling to Pennsylvania to promote his tax overhaul, not to campaign for Rick Saccone.Trump tweeted early Thursday that Rick Saccone “is a great guy” and said, “We need more Republicans to continue our already successful agenda!” The 59-year-old state representative faces Conor Lamb, a 33-year-old lawyer and former Marine, in the March 13 special election as Democrats look to build on their Senate victory in conservative Alabama and lay the groundwork for gains in the midterm contests in November.The president’s official mission during the trip to the Pittsburgh area was to praise recently enacted GOP tax cuts. Trump planned to appear with Saccone, though the White House had said the president wouldn’t be mentioning the candidate in his remarks. Trump was traveling to the 18th Congressional District, where GOP incumbent Rep. Tim Murphy resigned after admitting to an extramarital affair.The election is shaping up as the next test of Democratic enthusiasm and GOP resilience in the Trump era and an early indicator of whether a midterm wave may be coming in November, as Democrats hope. They want to want to show they can win in Trump territory without benefit of a scandal or flawed candidate, as was the case with Republican Roy Moore in the Alabama Senate election.“Will be going to Pennsylvania today in order to give my total support to RICK SACCONE,” Trump tweeted.Saccone, in an interview Wednesday, framed his candidacy as an extension of the agenda that propelled Trump. “It’s only natural to have him come out to see his core constituency and have us celebrate his successes with him,” Saccone said.The White House would confirm only that Saccone was to greet the president at the airport and attend Trump’s tour of a factory. Later Thursday, press secretary Sarah Sanders sent out a statement correcting Trump’s tweet.“While the president has made clear his support for Republican candidates throughout the country, including in Pennsylvania, the purpose of today’s visit is to promote the president’s successful agenda especially on taxes,” she said.Trump’s visit to the H&K Equipment Company in Coraopolis, Pennsylvania, has been billed as an official event, rather than a campaign stop. A campaign event would require that taxpayers be reimbursed for some of the expenses.Saccone, a retired Air Force officer with a doctorate in international affairs and experience in counterterrorism, said he didn’t know whether he would sit with the president or even get to spend any one-on-one time with him. “I don’t have any details,” he said after spending the day in Washington raising money with GOP House leaders.The Congressional Leadership Fund, a political action committee aligned with House Speaker Paul Ryan, R-Wis., has opened offices in the district with paid canvassers. Political groups bankrolled by the billionaire Ricketts family, owners of the Chicago Cubs, are airing television ads on Saccone’s behalf.As for Democrats, at the national party’s House campaign headquarters, spokeswoman Meredith Kelly praised Lamb’s “long record of public service to our country.” But the party hasn’t included the district on its official list of GOP-held targets, which now has 91 seats. Democrats must capture 24 GOP-held seats to regain a majority in the House.In 2017, Democrats managed surprisingly competitive races in four special congressional races in heavily Republican districts, but lost all four.Lamb must “run a perfect campaign,” said Mike Mikus, a Democratic campaign strategist who has run congressional races in the Pittsburgh area. “But it can be done,” Mikus added.Registered Democrats outnumber Republicans in the district by about 70,000, a reflection of organized labor’s influence. But many of those union households embraced Trump’s populist, protectionist message in 2016, and Mikus noted they’re also culturally conservative.Lamb and Democrats believe they have an opening that wasn’t available before, given that Murphy was among the few Washington Republicans who voted with labor unions and regularly got their endorsements.This time, the state AFL-CIO has endorsed Lamb, and he is trying to strike the tone Mikus says is necessary for a Democrat to win.Lamb’s first television ad, set to air Thursday, notes he has refused “corporate PAC money” and believes both parties “need new leaders in Congress.” That’s a reference to his promise to not to back House Democrat leader Nancy Pelosi for speaker. She is unpopular in many districts and the GOP regularly uses her as a cudgel on Democratic nominees.The 30-second spot also tells voters that Lamb grew up in the district and says he “still loves to shoot.”____Barrow reported from Atlanta. Associated Press reporters Marc Levy in Harrisburg, Pennsylvania, and Jill Colvin in Washington contributed to this report.