WASHINGTON -- A poll released just four days before Election Day showed U.S. Sen. Robert Menendez putting some distance between him and former Celgene Corp. executive Bob Hugin.

Menendez, the New Jersey Democrat seeking a third full term, led Hugin, his Republican challenger, among likely voters, 51 percent to 39 percent, in the Stockton University survey released Friday. Libertarian Party nominee Murray Sabrin received 3 percent.

As has been the case in earlier polls, Menendez has benefitted from antipathy towards Republican President Donald Trump, which has cancelled out voter angst over his own ethical problems.

"Even though his name is not on the ballot, President Trump's presence appears to be at the top of the ticket in New Jersey," said Michael W. Klein, interim executive director of Stockton's William J. Hughes Center for Public Policy.

"Our poll indicates that New Jersey's voters oppose the president, and the best way to express that opposition at the ballot box is to re-elect Senator Menendez, despite any misgivings they might have about the senator himself," Klein said.

An earlier Stockton poll released Oct. 1 had the race closer than any other survey, calling it a dead heat.

The poll was the most recent to show Menendez ahead of Hugin, who has spent $36 million of his own money, most of it on negative ads attacking the incumbent over his ethical problems. It gave Menendez a bigger lead than other recent surveys.

In this survey, 71 percent chose either Trump or party control of the Senate as their main factor in deciding which candidate to vote for.

Just 19 percent cited Menendez's ethical problems, which include a Senate Ethics Committee rebuke and a 14-count indictment that initially ended in a mistrial before a judge acquitted him of some of the charges and federal prosecutors dropped the rest.

Menendez was viewed unfavorably 44 percent of likely voters and favorably by 23 percent. Despite Hugin's ad blitz. Menendez's unfavorable ratings dipped from 54 percent in the earlier Stockton survey.

Just 37 percent rated Trump's performance in office as good or excellent, with 62 percent saying it was fair or poor.

While the race had been closer than expected, Hugin has never led in any poll. Still, Senate Democrats were concerned enough that their political arm and their super political action committee spent around $7 million on Menendez's behalf.

The Cook Political Report recently declared the race a tossup, but Inside Elections continued to rate Menendez as a likely bet for re-election. Nate Silver's FiveThirtyEight gave the incumbent a 91 percent chance of winning a third term on Tuesday.

The poll of 598 likely voters was conducted Oct. 25-31 and had a margin of error of 4 percentage points.

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