WASHINGTON -- The nasty race between Democratic U.S. Sen. Robert Menendez and Republican challenger Bob Hugin is now a tossup, as the Cook Political Report said the incumbent's ethics baggage could cost him the seat.

The Washington-based publication that tracks Senate races downgraded Menendez's chances less than two weeks before Election Day, citing little-known and unfunded community newspaper publisher Lisa McCormick's surprisingly strong performance in June's Democratic primary.

"The contest isn't about anything else but Democratic U.S. Sen. Bob Menendez and his ethics problems," said Jennifer Duffy, Cook's Senate analyst.

"The biggest threat to Menendez's re-election is not so much Hugin than it is the voter who goes to the polls and decides to send Menendez a message, much the way many did in the primary when 38 percent voted for his unknown primary opponent," she said.

Still, Inside Elections, which also tracks Senate races, said Menendez was likely to win re-election, and Nate Silver's FiveThirtyEight gave him a 90 percent chance of being re-elected. The Real Clear Politics polling average put him ahead by 7.7 percentage points.

Hugin has spent millions of dollars on ads bashing Menendez, making the race much closer than originally expected.

But Menendez, who has never trailed in any legitimate opinion poll, spent more money on ads in the closing weeks of the campaign than Hugin has, and got a boost when the Senate Democrats' super political action committee, Senate Majority PAC, said it would spend another $2.8 million on his behalf.

Federal Election Commission reports covering the period Oct. 1-17 and filed Thursday showed Menendez spending $4.3 million during the period, $3.9 million of that on political commercials. Hugin spent $5 million with $2.6 million going for advertising.

Overall, Hugin, a former Celgene Corp. executive, spent more than twice as much as Menendez through Oct. 17, $27.7 million to $11.8 million.

Helping to reduce spending gap were Senate Majority PAC, which has spent $5.8 million overall to help Menendez, and the Democratic Senatorial Campaign Committee, which spent $900,000.

Another super PAC, Patients for Affordable Drugs Action, spent $3.3 million to help Menendez.

Integrity NJ, the super PAC founded by allies of Gov. Chris Christie, spent $3.8 million on behalf of Hugin. Investment banker Nicholas Brady, a former U.S. treasury secretary and former interim U.S. senator from New Jersey, contributed $1.8 million.

Hugin's financial edge was due to the $31 million in personal funds he put into his campaign -- including $7 million so far this month -- allowing him to flood the airwaves with ads focusing on Menendez's ethical problems.

Menendez's trial on criminal corruption charges ended in a mistrial. The Senate Ethics Committee then rebuked him for intervening with federal agencies on behalf of Dr. Salomon Melgen, a friend and campaign donor who had given him gifts and trips.

Hugin's recent ads resurrected the unproven allegations that Menendez slept with underage prostitutes during a trip to the Dominican Republic with Melgen. The ads were criticized by independent fact-checkers.

The challenger raised $2.8 million from other sources and had $2.6 million to spend. Among his most recent contributors were Vice President Mike Pence's leadership political action committee, which gave the maximum $5,000 to his campaign.

Menendez raised $11.7 million for his re-election and had $1.8 million in the bank.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.