WASHINGTON -- A veteran of the last two Democratic presidential campaigns has become the first person to challenge U.S. Sen. Robert Menendez for his party's nomination.

Michael Starr Hopkins announced Sunday that he would seek the Democratic nomination against Menendez, who faces a retrial on criminal corruption charges and a Senate Ethics Committee investigation.

"How can we run against the corruption of Donald Trump if we're excusing corruption within our own party?" Hopkins said.

A lawyer, Hopkins worked on Barack Obama's and Hillary Clinton's presidential campaigns. He also has appeared on the Fox News Channel.

The Justice Department said it would again try Menendez on charges that he intervened with federal agencies on behalf of a friend and campaign donor, Dr. Salomon Melgen, a West Palm Beach, Florida, ophthalmologist.

The first trial ended with a hung jury and U.S. District Judge William Walls declared a mistrial. A juror said the vote was 10-2 for acquittal. Walls later threw out several charges in the indictment, though declined to dismiss the entire case.

Menendez said he plans to seek re-election regardless of the Justice Department's decision. Top New Jersey Democratic politicians have lined up behind him.

"The senator finds himself in a very difficult spot," Democratic consultant Glenn Totten said. "Even if he is innocent, his innocence does not protect him from the political arena. His opponents will go to great lengths to claim he's guilty."

Despite his ethical problems, Menendez, D-N.J., is considered a strong favorite to win re-election by the two Washington-based publications that track congressional races, the Cook Political Report and Inside Elections.

He begins with a multimillion-dollar head start, though not as overwhelming as in previous campaigns.

Menendez reported raising $5.6 million from Jan. 1, 2013, after his last campaign, through Sept. 30. Six years ago he raised $10.4 million during the same period He entered October with $3.9 million in the bank, compared to $6.9 million in October 2011, 13 months before his last re-election.

At the same time, 51 percent of New Jerseyans said Menendez shouldn't run again and 49 percent called for his resignation in a Rutgers-Eagleton poll taken after the mistrial.

That could worry Democrats, who have an outside chance of winning the Senate but are more concerned with protecting incumbents in states like West Virginia, Indiana and North Dakota and therefore don't want to have to worry about blue New Jersey.

"At a certain point, they might not be able to afford having a chance to lose the Menendez seat," Totten said. "Given the current situation, I think it's incumbent on the senator to search his soul and see if he wants to put him through this and the party through this. This is now coming down to a personal choice for the senator."

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