New Jersey voters will decide dozens of primary races by Tuesday, including closely watched showdowns among candidates hoping to take on two vulnerable freshman congressmen: Jeff Van Drew, a party-swapping Republican, and Andy Kim, a Democrat in a swing district.
But the primary was also drawing attention because of something that had never happened before in New Jersey: Almost all of the voting was being done by mail, with ballots that had to be postmarked by Tuesday.
As in other states, the coronavirus pandemic has upended the way New Jersey is holding its primary this year. Only about half of the state’s polling sites are open for the filing of provisional ballots, which are expected to be used by a small number of people.
Voters can also deliver ballots that were mailed to their homes more than a month ago to drop boxes set up in each county.
The results of the closest races will probably not be clear for at least a week as the ballots trickle in, making Election Day as much a referendum on the voting method as on the candidates who are running.
Gov. Philip D. Murphy has said he was watching to see how the voting went before determining how broadly to rely on mailed ballots for the presidential election in November, where the stakes will be much higher.
“We’re going to be watching very closely for any shenanigans that we hear about,” Mr. Murphy, a Democrat, said on Monday. “Any voter suppression. Anybody that’s trying to job the system.”
In states like Washington that have long embraced voting by mail, there has been no evidence that it leads to widespread fraud. That has not dulled sharp attacks by President Trump, who has made dozens of false claims about the process and had predicted that it would result in “the most corrupt election in the history of our country.”
In the midst of the pandemic, there was nothing normal about how candidates have campaigned. And Election Day itself veered sharply from the typical script.
There were no perfunctory photographs of candidates casting votes with their spouses and no insider buzz around victory parties or early poll results. Get-out-the-vote efforts began weeks ago, as campaigns were able to check on who had returned ballots and who had not.
Those who had not were targeted by telephone and text.
Hector Oseguera, 32, a lawyer who is challenging Representative Albio Sires in a Democratic primary in northern New Jersey, said his campaign had planned to send 500,000 text messages to voters in the two weeks before Election Day, with a goal of contacting each voter four or five times.
Representative Josh Gottheimer, 45, who is locked in a Democratic primary battle with Arati S. Kreibich, a neuroscientist and former council member in Glen Rock, said that his campaign had made more than 525,000 get-out-the-vote phone calls and had sent 220,000 texts.
The reliance on texting and calls is a departure from typical New Jersey elections, where campaigns work to mobilize and sometimes even drive voters to the polls.
Employees at election boards in New Jersey’s 21 counties were also in uncharted territory, having to confirm signatures on ballots while also tallying votes.
“This can serve as a test run for November,” said John Froonjian, the executive director of the William J. Hughes Center for Public Policy at Stockton University. “New Jersey has to be prepared to learn from what happens today and the next few days.”
Professor Froonjian moderated a three-way online debate last month between some of the Democrats competing to run against Mr. Van Drew, who was elected as a Democrat and joined the Republican Party in December after voting against Mr. Trump’s impeachment.
Mr. Van Drew’s campaign to win re-election will be one of the most-watched congressional races this year, and the Democratic primary to choose the candidate who will try to unseat him quickly turned toxic.
The race pits Amy Kennedy, a former middle school history teacher and mental health advocate who is married to a member of a Democratic political dynasty, against Brigid Callahan Harrison, a college professor who won the early support of South Jersey’s political power brokers.
Cricket Cohen, 71, who owns a horse farm in Atlantic County, where more than a third of the district’s voters live, recently planted a campaign lawn sign in support of a third Democratic challenger, Will Cunningham, 34.
Ms. Cohen said she was turned off by Ms. Kennedy’s and Dr. Harrison’s alliances with established party politicians. Ms. Kennedy, who is backed by Mr. Murphy, is married to Patrick J. Kennedy, a former congressman and a son of Senator Edward M. Kennedy.
A lifelong Democrat, Ms. Cohen said she had voted in 2018 for Mr. Van Drew, who she believes is vulnerable, even in a district where Mr. Trump beat Hillary Clinton by 5 percentage points.
“More people are disillusioned with Van Drew than I thought would be,” she said.
A Republican primary in a nearby South Jersey congressional district has also had its share of intrigue. A former business executive, David Richter, 54, who initially planned to challenge Mr. Van Drew in a general election as a Republican, switched districts after Mr. Van Drew switched parties.
He is facing a former elected county official, Kate Gibbs, who is 20 years younger. As a woman, Ms. Gibbs could appeal to female voters — a coveted group for Republicans hoping to expand their reach in New Jersey.
The winner will take on Mr. Kim, who narrowly won election in 2018 after a drawn-out campaign against a key ally of Mr. Trump’s.
Farther north, in New Brunswick, another young woman, Amani Al-Khatahtbeh, is trying to shake up the status quo in a Democratic primary against Representative Frank Pallone Jr., a 16-term incumbent who is seeking re-election again.
Ms. Al-Khatahtbeh, a founder of MuslimGirl.com, a blog for Muslim women, said she decided to enter the race amid the renewed focus on policing and racism that swept the nation in the aftermath of the killing in police custody of George Floyd. She said she had gotten a telephone death threat since entering the race, which she taped and shared on Twitter.
“This campaign is much larger than me as a candidate,” Ms. Al-Khatahtbeh, 28, said. “This is our generation stepping up and taking on the leadership that has failed us since we were children.”