Unlike the last special election in Pennsylvania, where the Democratic candidate Conor Lamb outraised Rick Saccone 3 to 1, Balderson was better suited to take on O'Connor financially, although he was still operating at a deficit.
Mr. Balderson and other Republicans claimed victory late Tuesday night, though no news organizations called the race and there remained an unknown number of provisional ballots still to be counted. "Now Troy wins a great victory during a very tough time of the year for voting", Mr Trump tweeted before the result had been announced. "He will win BIG in Nov".
Tonight, the OH special election widely seen as a referendum on President Donald Trump reaches its conclusion.
One of the primary season's true sideshows ended with a lopsided win - Rep. Ron Estes (R-Kan.), who won a 2017 special election in Kansas's 4th Congressional District, has defeated Ron M. Estes, who did not.
However, Tiberi resigned before finishing his term, forcing the special election to replace him. The Democratic candidate, meanwhile, vowed: "We're not stopping now". "Tomorrow we rest and then we keep fighting through to November", O'Connor told supporters at a post-election party.
"Tonight I am going to promise to you that I am going to work relentlessly, relentlessly for this 12th Congressional District", Mr. Balderson said at his election night party in Newark.
O'Connor seemed to have the momentum in the run-up to Tuesday's election.
The primary also is when the next congressman or congresswoman will effectively be chosen in two solidly Democratic U.S. House seats opening due to retirements, and when nominees will be selected for an open battleground district in suburban Detroit.
Trump won the district by 11 points in 2016. So, as Republicans like Ohio Gov. John Kasich - a vocal critic of Trump - pointed out prior to Election Day, the sheer fact that the race is so close should strike fear in the hearts of GOP operatives. Once they are tallied, an automatic recount would be triggered if the margin of results is within 0.5 percent. To overcome Colyer, Kobach will need to pull out strong numbers in Shawnee County and Sedgewick County, as well as in the west side counties of the state. But with 99 percent of precincts reporting, Delaware County had tilted in Balderson's favor.
Missouri Attorney General Josh Hawley is expected to take on McCaskill, and in MI, military veteran and business executive John James is vying for the chance to knock off Stabenow.
His favored candidate for MI governor, state Attorney General Bill Schuette, defeated Lt. Gov. Brian Calley to claim the GOP nomination.
Hours before polls opened, Trump again weighed in on Twitter, casting James as "a potential Republican star". James also had help in the state from musician Kid Rock, who had once flirted with running against incumbent Democratic Michigan Sen.
The five-way Democratic primary featured labour lawyer Brent Welder, who campaigned recently with self-described democratic socialists Vermont Sen.
On the left, candidates backed by Democrat-socialist darlings Alexandria Ocasio-Cortez and Bernie Sanders face off in key primaries in MI and Kansas.