Yet Saccone has underwhelmed national Republicans in this heavily pro-Trump district, and public polling ahead of the March 13 election has shown Saccone neck-and-neck with Lamb, a former federal prosecutor and Marine.
"Heading to Moon Township, Pennsylvania, to be with a really good person, State Representative Rick Saccone, who is running for Congress," Trump tweeted. "Big & happy crowd (why not, some of the best economic numbers ever). Rick will help me a lot. Also, tough on crime & border. Loves 2nd A & VETS."
The rally in Moon Township had originally been scheduled for mid-February but was postponed after the deadly school shooting in Parkland, Florida. The campaign statement announcing the new date did not mention Saccone; rather, it said Trump would come to Moon Township to tout the GOP's new tax law.
This is Trump's first campaign rally in more than three months.
PENNSYLVANIA'S TIGHT RACE
In the hotly contested special election in this southwest corner of Pennsylvania, one issue has universal support: President Donald Trump's tariffs on steel and aluminum imports.
Even as Republican Rick Saccone and Democrat Conor Lamb have fought over healthcare, taxes and guns, the two agree that the Republican president's tariffs are good for jobs and the country.
It's time to "take some action to level the playing field here," said Lamb, who endorsed the tariffs as soon as Trump announced them.
"This is a national security issue," Saccone said. "Believe me, no one wants to start a trade war. This is a very narrowly focused field that the president is touching on."
The unanimity in steel country stands in sharp contrast to how the tariffs have played in Washington and around the country. Trump's surprise move has scrambled party loyalties, upsetting Republican leaders fearing a trade war and attracting the support of Democrats determined to win back working-class voters in the midterm elections.
In the final days of this closely watched US House contest, the issue's resonance in Pennsylvania's 18th Congressional District underscored Trump's populist appeal, how he reconfigured the electoral map in 2016 and has redefined the Republican Party.
And yet, there are limits to Trump's support. Wednesday's race is a toss-up despite Trump's 19-point win in the district and millions of dollars of Republican-backed attack ads against Lamb. The 33-year-old Marine and former prosecutor has waged an energetic campaign against Saccone, 60, a state lawmaker.
Privately, Trump has cited the close race as a reason to move ahead on tariffs, and he rebuffed economic advisers who worry that they will kill more jobs than they create.
If Lamb wins, it will be a major setback for both House Republicans in their bid to hold the majority this November and the President.
And no matter the outcome, the frustration of the economy's forgotten prevails in this section of Trump country, fuelling a strong anti-establishment mood among the electorate.
Jim Walton, 53, a roofer who intended to vote for Lamb, said Americans have been "getting treated unfairly for years, and it's been sad. Even Bill Clinton - he was one of the better presidents we had in there - he signed that NAFTA deal that screwed a lot of us."
The nation's largest steel companies, based in this district that stretches from the Pittsburgh suburbs to the state's rural borders with Ohio and West Virginia, have welcomed the new policy. But there is little expectation of an overnight renaissance for the steel industry, which peaked in the 1960s.
Still, the concept of punishing foreign companies for taking advantage of American steelworkers was powerful, and it crossed partisan boundaries.
Democrats and union canvassers were optimistic that the tariffs would not change the trajectory of the race. Every major union, from the United Steelworkers to the United Mine Workers of America, had endorsed Lamb, citing Saccone's long record of antilabour votes. Workers who rejected Hillary Clinton in 2016 were willing to back Lamb.
Democrats, anxious about the president, were generally pleased by the tariff. Republicans, inclined to trust Trump more than any other member of their party, were overjoyed.
David Podurgile, 52, described a buoyant new mood at his employer, Murray Energy, since the administration relaxed regulations on the coal industry, and he gave the President the benefit of the doubt on tariffs.
"There's going to be pressure from other countries at the beginning, so maybe there's going to be a trade war, as they call it," he said. "But we've been treated so unfairly for so long."
Twenty years ago, 21,100 Pennsylvanians were employed directly by iron and steel mills. Ten years later, that number dipped to 13,600. At the start of this year, just 10,600 Pennsylvanians worked in that industry, down slightly since Trump's inauguration.
The state's unemployment rate, at 4.7 per cent, has returned to a level where it was before the Great Recession. Steel stopped being the region's major industry decades ago. For every worker employed by US Steel, nine work at the University of Pittsburgh Medical Centre; the United Steelworkers' most recent project in the region is not organising steelworkers but organising graduate students at Pittsburgh's major universities.
"The working class is undergoing a major redefinition right now," said Beth Shaaban, a 39-year-old doctoral candidate at the University of Pittsburgh. "We're obviously in solidarity with all workers who may be in those fields more traditionally associated with the USW."
But the idea of taking action to punish "cheaters" in the steel market is potent - so potent that local Democrats have had nothing bad to say about it.
Senator Robert Casey, (D), who faces re-election in this state that backed Trump, commended the president for taking "action to protect our steelworkers." Pittsburgh Mayor Bill Peduto, D, who once criticised Trump for invoking Pittsburgh as a reason to withdraw from the Paris Climate Accords, also praised the tariffs.
"There is no doubt that if we get a more level playing field, the opportunity to produce more steel is very real," Peduto told reporters this past week.
Outside Pennsylvania, Democrats in competitive races this November, such as Senator Sherrod Brown, Ohio, Senator Joe Donnelly, Indiana, and Senator Tammy Baldwin, Wisconsin, have offered similar praise.
Senate Minority Leader Charles Schumer, (D), has given them, and the President, bipartisan cover.
"I totally agree, wholeheartedly agree with President Trump's instinct to go after China," Schumer told the Washington Post. "All of these academics [say] anytime you try to do anything on trade, it's protectionist. They ought to not let that deter them, but they ought to put together a real plan that works."
The tariffs have faced resistance from Republicans. House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell opposed the move, fearing a reciprocal response from other nations on US products such as Harley-Davidson motorcycles and Kentucky bourbon.
