Businessman Tom MacArthur won the Republican nomination for New Jersey’s 3rd district Tuesday night, setting up Republicans with their best shot at holding onto retiring Rep. Jon Runyan’s (R-N.J.) competitive seat.

MacArthur took 60 percent of the vote to 2013 GOP Senate candidate Steve Lonegan’s 40 percent of the vote when the Associated Press called the race.

MacArthur was national Republicans' preferred candidate, fearing that the polarizing and conservative Lonegan would make it harder to hold onto the seat. 

Their primary battle was one of the nastiest in recent New Jersey history, with both candidates trading charges of dishonesty and personal jabs.

Lonegan called MacArthur a “monster” for allegations his former insurance company delayed or refused payments to victims of a California wildfire, an accusation that featured prominently in one of Lonegan’s attack ads.

In response, MacArthur filed a defamation suit against his opponent, and told a local paper Lonegan had “become a callous, angry person.”

Even Runyan said the race had become “nasty as hell.”

He, along with most of the GOP establishment in the district, endorsed MacArthur, wary of the possibility that Lonegan’s penchant for off-color remarks could cost them the seat if he made it through the general. 

Lonegan, for his part, nabbed the backing of former Alaska Gov. Sarah Palin, and touted the fact that he won the district during his 2013 run for Senate against Democrat Cory Booker.

A Democratic group, Patriot Majority USA, also waded into the primary. In a move seen as intended to boost Lonegan, the group launched attack ads that knocked Lonegan for his “conservative” positions and charged MacArthur supported raising taxes.

But MacArthur’s substantial personal wealth — he invested $2 million of his own money into his bid, and says he’ll spend more if he needs to — and his establishment backing helped deliver him the win.

He’ll face Burlington County Freeholder Aimee Belgard, considered a top-tier Democratic recruit, in the general, for what's expected to be a top-targeted race. 

Democrats have long targeted the 3rd district, which has traditionally been represented by Republicans but voted for Obama in 2008 and 2012, and with Runyan’s retirement their chances at picking up the seat have improved.

Elsewhere in New Jersey, with support from local and national progressives, Assemblywoman Bonnie Watson Coleman won the Democratic primary in the state’s 12th district, left open with Rep. Rush Holt’s (D) retirement decision. She’s expected to easily retain the seat.

And in the 1st district, currently open due to Democratic Rep. Rob Andrews’ resignation earlier this year, State Sen. Donald Norcross easily won the Democratic primary. He’ll go on to face former Philadelphia Eagles player Garry Cobb in the general, but the seat is expected to stay in Democratic hands.

—This piece was updated at 10:37 p.m.