Tuesday's election is being watched as a potential harbinger for November's congressional elections.
Lamb has run as an independent-minded figure.
In contrast, as of February 21, Saccone has raised only $917,000 - only $116,000 of which came in the form of unitemized contributions from small donors. They've painted Lamb as a lackey of House Democratic leader Nancy Pelosi of California and weak on immigration.
And Kennedy said that if Lamb wins, it could send the opposing party a big message.
Moulton "could be very well-positioned if this works out", said Hank Sheinkopf, a Democratic political consultant.
Ingeborg Moran, 27, is also supporting Lamb.
"He puts his money where his mouth his", Lamb said about Moulton. "And this guy can really help me".
Trump won the district by almost 20 percentage points against Democrat Hillary Clinton in 2016.
According to a March poll from the Pew Research Center, 62 percent of millennials said they would prefer the Democrat on a generic ballot, compared to 29 percent who would prefer the Republican candidate.
He even traveled to the state Saturday to hold a raucous campaign-style rally, at which he mused on topics including giving drug dealers the death penalty, Celebrity Apprentice ratings, and the supposed attractiveness of his younger self.
Donald Trump Jr. toured Sarris Candies in Canonsburg Monday afternoon, sampling chocolates and ice cream while criticizing Democrats and encouraging the company's workers to vote for congressional candidate Rick Saccone.
Joseph DiSarro, professor of political science at Washington & Jefferson College, said the projections of a millennial blue wave may not apply in the western Pennsylvania race.
The race to replace Murphy, who resigned after allegedly suggesting mistress should have an abortion, will be between Democrat Conor Lamb and Republican Rick Saccone. An upset would embolden them as they look to win in places where the party has lost ground in recent decades, and it would spook Republicans about their prospects in this tempestuous era of Trump. The 18th district won't exist next year due to a Supreme Court decision ordering the map to be redrawn. That made a lot of Democrats feel good, but the grown-ups in the party quickly understood what an absurd notion it was, and turned to winning the inevitable special congressional elections made necessary by deaths and resignations. "No matter what happens in Pennsylvania, there should be no reason this race is as close as it is".
A Monmouth University poll on Monday showed Lamb ahead.
The stakes are high for US President Donald Trump and congressional Republicans in tomorrow's special election to fill a US House seat, with GOP leaders unnerved about the prospect of defeat and the implications for this year's midterm elections. Trump namechecked two California congresswomen, raising the warning of a Democrat-controlled House. In fact, images of Pelosi, that bogeywoman of the right, her mouth pinched, her visage darkened, are featured in most GOP anti-Lamb spots.
He has been considered by some to be a test case of Moulton's brand of antiestablishment rhetoric.
However, former federal prosecutor Lamb, who comes from Mt. Lebanon, one of the richest neighborhoods in the district, has not always had such an easy relationship with organized labor. Vice President Joe Biden, who was born in Scranton, has campaigned with him.
"In a time when they are trying to divide us, when our country is so divided already, we are united in this district for the first time in a long time", Mr Lamb told the steelworkers.
The president's son was the latest in a line of national pro-Trump figures to appear with Saccone, a strong Trump supporter who boasts one of the most conservative voting records in Pennsylvania's Legislature.
Republicans have suffered major losses during Trump's presidency, including a blowout in the Virginia gubernatorial race and a loss in Alabama's Senate race. He also has a military background, having served in the Air Force. "They have a hatred for our president".
If he loses, it could foreshadow what is already expected to be a hard midterm election cycle for Republicans. "That's why they call them special", former Trump campaign adviser Ed Brooker said, reflecting the mood of Trump's political circle on the eve of the election.
Asked about Republican criticism of Saccone's campaign, Trump told reporters, "God knows, if it's going to make it hard for Trump, the media's going to be all over it".
In an effort to downplay expectations, GOP chairwoman Ronna McDaniel has said she expects it to be a "tight, tight race". "This election is going to give us insight into that", he said.