His explanation for his exit has been met with skepticism by good-government groups and, privately, some fellow Democrats.
Andrews, after all, seemed to love the House. He was rising in stature, and his close ties to Pelosi, the minority leader, gave him a prime seat within Democratic circles.
But looming in the background was a House ethics committee inquiry that has ground on for more than two years. Andrews' departure will end the investigation, because the panel has jurisdiction only over members of the House and their staffs.
Most lawmakers who quit Congress finish their terms. Andrews plans to leave Feb. 18. Even some of his staff was caught off guard, and learned of his plan through news reports.
Andrews has firmly said his decision was not about the investigation. "Absolutely not. Let me be very clear about that - no," he said Wednesday.
Staying in Congress would mean borrowing to pay an estimated $750,000 in undergraduate and medical-school costs for his daughters, 19 and 21, he said Friday in an interview. His new job means paying as they go.
"We'd rather not bury ourselves or our kids in debt," Andrews said. "I think it's a choice my constituents understand."
Ethics watchdog groups questioned his explanation.
"The fact that he resigned in the middle of his term suggests rather strongly that the House ethics committee was about to come out with a very unfavorable report and probably issue some penalties," said Craig Holman of the consumer group Public Citizen.
Andrews said he had to move quickly because the job at Dilworth would not be open after March.
In private conversations last week, many Democrats backed up his statements while others questioned his timing. All expressed shock - except for close advisers and loved ones, no one saw it coming.
"Only he and his wife and possibly a small group of people know the circumstances," said one New Jersey Democrat.
A long investigation
The ethics questions began in late 2011, when the Star-Ledger of Newark revealed how Andrews used campaign funds to pay for a family trip to Scotland that year. He, his wife, and their daughters spent $30,115 on business-class flights, three nights at the five-star Balmoral Hotel, and other expenses while attending the wedding of a political consultant.
Andrews has said that the trip was to improve his relationship with the consultant, and that he followed all rules and regulations for use of campaign funds. The nonpartisan Office of Congressional Ethics found "substantial reason to believe" he had misused campaign money "in violation of House rules and federal law." That report set in motion the ethics committee's probe.
A committee statement issued last March added this twist: the question of whether Andrews had "made false statements to federal officials." The panel has made no public comments since.
It's not clear what clues, if any, Andrews had of the panel's intentions. A lawmaker facing potential sanctions gets at least 40 days' notice - but it's not known if that happened in this case.
Typically, lawmakers under scrutiny can also get a feel for an inquiry's direction from interactions their lawyers have with investigators, said Rob Walker, a former chief counsel to the House and Senate ethics committees. "The member likely is going to have at least some idea of what way the wind's blowing," said Walker, now at the law firm Wiley Rein.
For his part, Andrews said he had no notice of any impending action. "The committee has said nothing to us about anything being the next step," he said Wednesday off the House floor. "Not at all."
Colleagues approached to wish him well.
The Dilworth offer
When Dilworth Paxson, a storied Philadelphia firm, approached him in January to talk about heading its government affairs team, Andrews said, he thought of his daughters.
Paying for their schooling "is a central issue in our life," he said.
Andrews' House salary is $170,000. In 2012, his wife, Camille, earned roughly $167,000 as associate dean of Rutgers-Camden Law School. An additional $105,000, plus $60,000 in stock options and stock awards, came from her role as a director at Marlton-based Hill International, a project management and construction claims consulting company, its public filings show.
Camille Andrews also earned $10,000 between July 2011 to June 2012 as a director of the Ayco Charitable Foundation, working there an average of an hour per week, according to its tax filings.
The couple's combined 2012 compensation from those sources was $512,000.
Camille Andrews was also listed as counsel at a Bala Cynwyd firm, Context Capital. Her pay there is not public.
'Rob made a decision'
Even in political circles, word of Andrews' resignation didn't spread widely until Monday night. "Our Monday morning conversation was the first time I became aware he intended to resign," said Norcross, who is also majority owner of the company that publishes The Inquirer.
State Senate President Stephen Sweeney (D., Gloucester) found out around 10 p.m. "Rob made a decision, and I had no reason to doubt him," he said.
Bill Caruso, Andrews' longtime confidant and former chief-of-staff, said Andrews "put his family in front of his career."
State Sen. Donald Norcross (D., Camden), who is George's brother, swiftly declared his candidacy for Andrews' seat. Ex-Eagle Garry Cobb said he plans to run as a Republican.
Andrews will continue to live in South Jersey, but said he will work mostly out of Washington.
There is still a complaint pending with the Federal Election Commission. The House ethics panel also has the option, with a two-thirds vote, to send information to the Justice Department - but there has been no sign that any criminal investigation is underway. Andrews said neither he nor his attorney had heard of any such inquiry.
"Absolutely, without condition or reservation, the answer is no," he said.
His departure, one South Jersey Democrat said, is typical of a man known for keeping his own counsel.
"When Rob makes a decision, he's gone," said the fellow Democrat. "He's already two steps down the field, and you're trying to figure out what he did."