CHICAGO (CBS)–Illinois has a new governor. With most polls now closed in Illinois, Democratic challenger for governor J.B. Pritzker has defeated Republican incumbent Bruce Rauner.

With 84 percent of precincts reporting, Pritzker led Rauner with 55 percent of the vote. Rauner had 39 percent.

The race between Rauner and Pritzker was one of the most expensive governor’s races in U.S. history, with the candidates spending more than $259 million combined as of late last week.

Since the start of 2017, Pritzker has spent about $171 million on the campaign, largely from his own personal finances. Rauner has spent $71.5 million of his own money on the race.

Rauner conceded shortly before 8 p.m. Tuesday night at his campaign party headquarters at the Drake Hotel, and most of his crowd of supporters had dismantled within two hours.

“Now we stand not as Republicans or Democrats, but as the people of Illinois,” Rauner said in his concession speech. “Now is the time to move forward. We have made great progress in the last four years, but we cannot let this progress end.”

RELATED: Complete Illinois Election Results 

The state’s new Governor-Elect is the billionaire heir to the Hyatt hotel fortune, and has given at least $146 million to his campaign. Rauner, a multimillionaire equity investor, pumped at least $50 million of his own money into his campaign.

A host of prominent Illinois democrats turned out for Pritzker’s campaign party at the Marriott Grand Marquis Hotel, including Ill. Sen. Dick Durbin, who took the opportunity to take a final jab at Rauner.

“Bruce Rauner hates labor unions,” Durbin said. “His day is over (and) our future with J.B. lies ahead,” Durbin said. “Last night we were in Peoria. JB said, ‘are you ready for the fight?’Today across Illinois, people were ready for the fight.”

Before a sea of balloons and confetti fell from the ceiling on a packed room of democratic supporters, Pritzker thanked his fan base and embellished many of the state’s major moments in history, from the Cubs winning the World Series to the Obama’s and Oprah Winfrey calling Chicago home.

“Democrats across the state, from statewide to county races, because of you–you all won the Game of Thrones award tonight,” Pritzker said.

Pritzker thanked Rauner and wished him and his family well, but focused most of his speech on his plans for Illinois.

“Throughout this campaign, I have asked this question–‘are you ready for the fight?'” Pritzker said.

He revisited the main issues he ran his campaign platform on, including healthcare, education, equal pay, gun safety, strong unions and immigration reform.

While Pritzker held a strong lead in the polls leading up to the election, the campaign remained especially heated, with Rauner repeatedly painting Pritzker as a corrupt insider too closely tied to Illinois House Speaker Mike Madigan – Rauner’s longtime political nemesis – and Pritzker has called Rauner an utter failure as governor.

Pritzker was hit with a pair of October surprises in his bid for the governor’s mansion: a finding by the Cook County inspector general that he engaged in a “scheme to defraud” taxpayers by using a loophole to avoid paying more than $330,000 in property taxes on a Gold Coast mansion; and a lawsuit by several campaign staffers accusing his campaign of racial discrimination.

Pritzker has insisted he obtained his property tax breaks through a routine appeal process, and followed all the rules, but paid back the tax break. He also denied any discrimination by his campaign, and has vowed to fight the lawsuit in court.

Rauner faced a crisis of his own late in the campaign, when Illinois Attorney General Lisa Madigan launched a criminal investigation into his handling of a deadly Legionnaires’ disease outbreak at a state-run veterans’ home in Quincy.

The Legionnaires’ outbreak has led to 14 deaths since 2015, and Rauner has been sharply criticized for how his administration handled the crisis, including whether it notified the public in a timely enough manner. The governor has called Madigan’s criminal investigation a “political ploy” and a “shameful abuse of power.”

Rauner also faced the additional challenge of a Republican state lawmaker joining the race as a third-party candidate, targeting conservative voters upset with Rauner’s decision last year to sign legislation that expanded taxpayer-subsidized abortions.