New Jersey hasn’t elected a Republican to the Senate in 46 years. But this fall, Democratic Sen. Bob Menendez is facing an unexpectedly strong and well-funded challenge from a Republican nominee named Bob Hugin, who is spending millions on negative ads reminding voters of Menendez’s past ethics troubles.

Menendez went on trial in federal court last year, accused of illegally accepting gifts from a wealthy donor. A mistrial was declared after the jury failed to reach a verdict, but later, the Senate Ethics Committee “severely admonished” Menendez.

“This guy is an amazing textbook picture of corruption,” Hugin said in a phone interview with Fox News this week, arguing Menendez has “embarrassed the state in so many different ways.”

To an extent, New Jersey's race represents the inverse of what is happening in Texas, where Democratic Rep. Beto O’Rourke is mounting a longshot but highly visible challenge to Republican incumbent Sen. Ted Cruz. Democrats are dazzled by the possibility of claiming a seat in deep-red Texas, however unlikely.

Deep-blue New Jersey hosts a similarly uphill climb for Republicans. No polls have shown Hugin in the lead. Fox News Power Rankings ranks the race “likely Democrat.”

“The senator has always taken every race seriously, and he’s never taken a single vote for granted,” Menendez campaign spokesman Steven Sandberg said in an interview. “He’s certainly fighting for those votes and he expects -- as we all do at the end of the day -- that he’s going to be victorious on Nov. 6.”

Still, while the Cruz-O'Rourke race has grabbed headlines for months, the threat to Democrats posed by Hugin has captured less attention. A GOP upset in New Jersey – where a Republican was last elected in 1972 – would not only shock observers but likely cripple Democratic hopes of retaking the Senate. The RealClearPolitics polling average has Menendez with a 7-point lead – substantial, but not necessarily comfortable. Menendez defeated his Republican opponent by 20 points in 2012.

Michael W. Klein, interim executive director of the William J. Hughes Center for Public Policy, said in a statement earlier this month the race is "up for grabs." His center's polling unit released a poll reflecting a dead heat, though it was an outlier in comparison with other recent surveys – for instance, a CBS News poll putting Menendez ahead by 10 points.

For the New Jersey senator, the race represents the latest in a series of dramatic fights for his political life.

Had he been convicted last November, Menendez could have faced expulsion from the Senate. Having survived the trial, Menendez famously suggested he was out for vengeance.

"To those who were digging my political grave so they could jump into my seat, I know who you are and I won’t forget you,” the Democratic senator said last year.

Menendez has adopted an aggressive tone, including recently tweeting out video of him calling the FBI’s recent background probe into Supreme Court nominee Brett Kavanaugh a “bulls--- investigation.”

Hugin, a retired Marine and biopharmaceutical company executive, has spent $15.5 million through June of his own money to draw attention to Menendez’s corruption trial. In an interview, Hugin said Menendez “abused the power of his office” and “disgraced the Senate.”

But Hugin is also using ads to brand himself a “different kind of Republican.” Hugin told Fox News he believes in a “strong national defense” and “economic liberty,” but he’s also pro-choice, pro-gay marriage and believes in “in equal pay for equal work.”

The Menendez campaign accused Hugin of “hiding behind” the attacks over the bribery trial, rather than focusing on issues.

“He has not taken definitive positions on issues that New Jerseyans care about,” Sandberg said, calling Hugin a “Trump Republican through and through.”

Hugin has never been elected to office before – but he and Menendez go back: they both grew up in Union City and served on the board of education together as students.

Asked about his recollection of Menendez at the time, Hugin, after a lengthy pause, would only say: “He was very interested in politics.”

Meanwhile, Hugin said there are no plans to have President Trump campaign on his behalf. But he said he hopes more national Republicans come to his side, referencing the money spent by the Democratic Senatorial Campaign Committee on Menendez’s behalf.

“It’s not President Trump,” Hugin said. “We haven’t really had any outside people get involved. We think it’s best to keep it focused on New Jersey.”