Later that day, Jon Runyan, his GOP opponent, accused him again of propping up a fake tea party candidate. The Republican State Committee called for a federal probe.
At debates, editorial board meetings, and public forums, Adler, 51, has been hounded about his links to independent candidate Peter DeStefano. But his undoubted frustration has elicited none of the anger often shown by candidates unable to move past an unwelcome subject.
This is politics, a game Adler has played since 1987 when he was first elected to the Cherry Hill Council.
Though he has been in dogfights, he hasn't bared his teeth. Cool under pressure, he breaks from his polished persona only to crack a joke.
The Cherry Hill resident is in a bitter and increasingly close race to win the Third District, which covers Burlington and Ocean Counties and includes Cherry Hill in Camden County.
A native of Northeast Philadelphia, Adler grew up in leafy Haddonfield. He played soccer and starred in a school play during his senior year at Haddonfield Memorial High. In the afternoons, he worked at his father's dry-cleaning store on Kings Court in the center of town.
"I would characterize it as work. My father, if he were alive, he would characterize it as my goofing off while he was working," Adler joked.
"I would turn the lever, the shirts would go round the carousel. He would yell at me to stop doing that. He would turn his back, and I would do it again, and he would yell again. . . . I think my role was to hang out with my father."
An only child, Adler lost his father to heart disease when his father was 47. The elder Alder had suffered his first heart attack four years earlier, when his son was 12. His second was so severe that he couldn't return to work, and the family lost its store.
John Adler's mother never recovered from the loss.
"She was broken in a way that, sadly, some people are when they lose a spouse," Adler recalled.
Despite personal tragedy, he earned high grades and enjoyed a typical suburban adolescence filled with parties and sports.
Michael White, a friend from high school, recalled Adler as one of the brightest kids in the class, but one who was never a jerk about it.
"He's a real guy. You would never know he's so smart. He's not pedantic," said White, of Haddonfield. "He's a very empathetic person."
As an undergraduate, Adler attended Harvard University on a scholarship and worked as a dishwasher, housepainter, and file clerk to make ends meet. Later, in Harvard Law School, he taught prep classes for the Law School Admission Test.
His future wife, Shelley, was a fellow law student. Raised an Episcopalian, Adler converted to Judaism when the couple married in 1985. They and their four sons, ages 9 to 21, live in Cherry Hill, where Shelley Adler was a councilwoman and continues to practice law part time. Their two youngest attend public school in the district; the older boys are in college.
One of the couple's sons got a shout-out from Shelley Adler's brother, Steven Levitan, cocreator of the ABC comedy Modern Family, last season when a character tried to duck out of dinner at Grandpa's so she could attend a party thrown by "Andrew Adler."
On the campaign trail, John Adler jokes about marrying a fellow Harvard law student.
"We thought, 'My God, we're set for life,' " he quips. "It turned out we had a lot of student-loan debt."
Adler's dual Harvard degrees could have earned him millions, say his friends.
"He is somebody who could do other things. He chose to be in the world of public service," said neighbor Perry Weinstock, a close friend and head of cardiology at Cooper University Hospital.
Adler said his experience after his father's death - when he and his mother lived on Social Security and he took federal college loans to supplement his scholarship and part-time jobs - explained his career decision.
Those government programs "allowed me opportunity," he said. "I always felt it was my obligation to create opportunity for others so others could have their chance to thrive."
He mixed a practice of business law with ever-higher aspirations for political office. Adler started on the Township Council in Cherry Hill in 1988 and two years later ran unsuccessfully for the U.S. House. He won a state Senate seat in 1991. In 2003, he opened a fund-raising committee for U.S. Senate but never declared his candidacy.
As a member of the minority party in the Statehouse in the 1990s, Adler said, he learned quickly to work with Republicans. He is best known for passing a ban on indoor smoking that was cosponsored by State Sen. Thomas H. Kean Jr. (R., Union). When Democrats took control of the Senate, Adler led the powerful Judiciary Committee.
By 2007, he was on track to run again for the House, and this time he had strong support from the Democratic Congressional Campaign Committee. Adler had no opposition in the 2008 primary and ample help in fund-raising. And he had Barack Obama at the top of the ticket in a year when voters were itching for change.
After winning that race, Adler got back on the trail in the historically Republican district. He visited with voters to discuss the coming changes in health care and made alliances with veterans, a small but vocal group in the district, which includes Joint Base McGuire-Dix-Lakehurst. He was appointed to the Financial Services Committee and is the only member of New Jersey's delegation to serve on the Veterans Affairs Committee.
When Congress is in session, Adler inflates an air mattress and sleeps in his office. But "I don't want to exaggerate my small sacrifice," he said, acknowledging the military.
He calls himself a centrist in an increasingly hostile Washington environment. In the House, he broke with his party to oppose the health-care overhaul because he did not think it would do enough to make care affordable for families and small businesses.
Voting with Democrats, he supported the $860 billion stimulus legislation, but he pointed out that he had supported fewer than half of the spending bills presented to Congress during his tenure.
His health-care vote cost him some support from the liberal wing of his party.
"I think he's been pragmatic and moved himself more toward the right," said Steve Stern of Mount Laurel, who blogs for the liberal BlueJersey.com website.
"It's probably something he needed to do but something that was disappointing to us. . . . Here's a guy we voted in to make some change and work with President Obama, and he kowtowed to the right wing," Stern said.
The Third District voted for Obama in 2008, and for Republican Christopher J. Christie in 2009. Independent polls show that this race is so volatile, a self-proclaimed tea party candidate could tilt the balance in Adler's favor. (Runyan has the endorsement of several area tea party organizations.)
The matter of whether Adler's supporters propped up DeStefano as a stalking-horse candidate to hurt Runyan could remain a mystery.
Adler "can't give a definitive answer - not because he doesn't want to, but because he can't give an answer to what other people might have done," said Sharon Schulman, director of the Hughes Center for Public Policy at Richard Stockton College.
The issue, Schulman said, is unlikely to go away.
Contact staff writer Cynthia Burton at 856-779-3858 or firstname.lastname@example.org.