“A lot of money and a lot of power was used against me, quite frankly, to remove me from my seat during a difficult year,” Mr. Van Drew said in an address to supporters late Tuesday, which his campaign manager, Ron Filan, said was a declaration of victory.
“But the truth is, we believed,” he added. “We believed in the America that we know, the America that we love, the America that we know is this great place.”
Mr. Van Drew was able to overcome the stigma of switching parties, buoyed by Mr. Trump’s warm embrace in a district that the president won by about five points in 2016. Comparable results for Mr. Trump in the district this year were not available.
In another close congressional contest in South Jersey, Representative Andy Kim, a first-term Democrat, defeated David Richter, a wealthy Republican businessman who similarly yoked himself to Mr. Trump during the campaign.
Representative Tom Malinowski, a first-term Democrat who, like Mr. Kim, was elected two years ago in a so-called blue wave aligned against Mr. Trump, defeated Thomas Kean Jr., the minority leader of the State Senate.
In other races, Representative Mikie Sherrill, a first-term Democrat and former Navy helicopter pilot, beat Rosemary Becchi, a tax lawyer, and U.S. Senator Cory Booker, a Democrat, was re-elected in his race against the Republican candidate, Rik Mehta, a biotech entrepreneur.
The election in New Jersey was conducted mostly by mail and yielded a voter turnout that Gov. Philip D. Murphy said on Thursday would exceed four million and be the highest in the state’s history.