Lamenting he had "let down" his supporters, Republican Bob Hugin conceded the U.S. Senate race to Democratic incumbent Robert Menendez on Tuesday night, ending one of New Jersey's most bitter contests.

And Hugin kept to the tough talk about Menendez he'd repeated countless times during the campaign.

"The people of New Jersey deserve better (than Menendez)," Hugin said during his concession speech at a Mountainside restaurant. "I let you down."

The thinning crowd that stuck around for his speech at 10:12 p.m. cheered him on and even broke into a chorus of "lock him up," aimed at Menendez.

"I'm so disappointed, we came up short," Hugin said. "I am proud of the campaign we have all run. There's lot of challenges, affordability and the failure to deliver for our people. I promise you, I will continue to fight for those issues."

The battle of the Bobs pitted two-term incumbent Menendez against Hugin, a retired pharmaceutical executive who had never run for office. Borrowing from his service as an active duty infantry officer, Hugin pitched himself to New Jersey voters by telling them to "Send in a Marine."

Yet Hugin's campaign will likely be remembered for its vitriolic ads reminding voters that Menendez had been indicted on federal corruption charges. Ultimately he was acquitted at trial on some counts while the jury deadlocked on others. The Senate Ethics Committee "severely admonished" him.

Hugin also ran ads featuring the unproven allegations that Menendez was involved with prostitutes during trips to the Dominican Republic with friend and campaign donor, Dr. Salomon Melgen.

Hugin said he was proud of his campaign. "I have my self-respect today," he said.

Menendez's ethical baggage made what should have been a cakewalk into a nail-biting uphill slog for most of the campaign. But because President Donald Trump is deeply unpopular in New Jersey, Hugin could not overcome even a weakened Menendez.

Trump's divisive rhetoric made it harder for Hugin to be heard, state Assembly Minority Leader Jon Bramnick, R-Union, said.

"I think Hugin is a class guy, but I think it's very difficult in a blue state, where you have a president who may be right on the policy but is wrong on the personality," Bramnick said.

"One thing in politics -- don't get people mad," he added. "They may not like you. Don't make them hate you. If you make people hate you, they will respond."

Until the final days of the campaign, pollsters and political scientists suggested Hugin was running a close race and could become New Jersey's first Republican U.S. Senator in 46 years. But Hugin never led in any poll, and on Monday, Quinnipiac University's poll said Menendez was 15 points ahead.

Early Monday night, around 8:15 p.m. Hugin and his wife, Kathy came out to greet the jovial crowd at the Stage House Tavern in Mountainside. Typically candidates sequester themselves until the race is called, but Hugin said he wanted to express his thanks and explain how he could not allow Menendez go unchallenged.

"New Jersey. deserves better," Hugin said. "New Jersey is a great state headed in the wrong direction and we are going to turn it around."

Moments after they left the stage, numerous TV networks declared Menendez the winner. The Hugin camp declined to concede for two hours, saying it was too close to call.

Susan K. Livio may be reached at slivio@njadvancemedia.com. Follow her on Twitter @SusanKLivio. Find NJ.com Politics on Facebook.