This analysis was first available to Bloomberg Government subscribers.
The hullabaloo over the election is particularly interesting considering the district itself will soon disappear because of a court mandate that Pennsylvania redraw its congressional maps after years of Republican gerrymandering.
President Donald Trump is highlighting a Pennsylvania newspaper's endorsement of the Republican candidate in Tuesday's special election for a U.S. House seat.
Pennsylvania Democrat Conor Lamb, the upstart attorney and former Marine who has surprisingly closed the gap in a deep-red congressional district, is one of the dozens of former service members Moulton has endorsed for Congress in the run-up to the 2018 midterm elections. In 24 consecutive special House elections, the party defending the vacant district has been victorious, according to data compiled by Bloomberg Government. "They have a hatred for our president". Former Vice President Joe Biden recently campaigned with Lamb.
"We're very concerned about this race", one national Republican involved in the campaign told TPM.
And beyond that, Trump in Pennsylvania said several headline-grabbing things that had nothing to do with the race and instead completely upstaged the candidate that Trump was ostensibly there to help - from praising North Korean dictator Kim Jong Un to calling NBC News' Chuck Todd a "son of a bitch" to getting behind a deranged proposal to execute drug dealers. "It would mark an extraordinary swing from Trump's almost 20-point victory here in 2016 if he could hold on to win".
The group confirmed the existence of the mailer to ABC News but declined to describe it or where it was sent in the 18th Congressional District.
Mr Lamb has resonated with voters, including some centrist Republicans. He also avoids criticizing Trump. "They have to get out there, they have to continue this fight, now, for the rest of '18, in '20 and in eight years we can make a big difference".
Lamb defended gun rights and opposed a proposal to raise the minimum purchase age for a rifle to 21, but promoted a universal background-check system with "no loopholes, period".
Saccone's greatest obstacle during this race - and the primary reason he's facing an unexpectedly tough challenge from Lamb - is his opponent's fundraising powerhouse. "We don't need people who are just going to follow the Manchins and the Testers and vote with Nancy Pelosi and Chuck Schumer". Saccone is struggling in a district he should win easily.
However, when it comes to campaigning, Saccone diverges with Trump's successful strategy of running as an outsider, instead boasting of his decades of experience in Pennsylvania politics.
In an effort to downplay expectations, GOP chairwoman Ronna McDaniel has said she expects it to be a "tight, tight race".
In spite of that applause, union veterans in attendance said that while they may be excited about defeating Rick Saccone, they aren't naive, either.
"Lamb will always vote for Pelosi and Dems...." In the final 10 days of the campaign, Republican advertising shifted from taxes to public safety, attacking Lamb's record as a prosecutor. Last month, Lamb's image rating stood at 49 percent favorable, versus 31 percent unfavorable. It's about 93% white and only about 36.5% of the population graduated from college.
"This district has voted overwhelmingly Republican in recent elections, but a large number of these voters have blue-collar Democratic roots". The flyer, obtained by ABC News, reads: "THANK YOU CONOR LAMB FOR OPPOSING GUN RESTRICTIONS".
National Republicans have done everything possible to save the district.
Tuesday's special election is for residents of southern Allegheny County, as well as parts of Green, Washington and Westmoreland counties. And if Pelosi were in charge of the House, Trump said, Lamb would simply "vote the party line".
Win or lose tomorrow, Lamb could run in November in a reconfigured district, numbered the 17th, where Rep. Keith Rothfus (R) is expected to seek re-election.
Lamb has run to the right of mostDemocrats on a series of issues.