On the night of the general election November 3, Democratic State Assembly candidate Andrew Zwicker made a speech in which he conceded to incumbent Republican Donna Simon in the 16th District race. But a week makes a difference. At press time Tuesday, Mr. Zwicker’s lead over Ms. Simon had risen to 78 votes after the provisional ballots in Mercer County were counted.

While the election has yet to be certified and Ms. Simon has neither conceded nor challenged the results, Mr. Zwicker, a physicist at Princeton Plasma Physics Laboratory, appears to be the winner in the race. The Republican party has until next Wednesday to file for a recount.

Win or lose, Mr. Zwicker is elated with the response he received and the manner in which his supporters helped run his campaign. “When a margin of victory is this small, that cliche that every vote matters is so incredibly true,” he said. “We knocked on thousands and thousands of doors and made thousands of phone calls. We got the message out about evidence-based decision making, and it resonates with people.”

Mr. Zwicker, who lives in South Brunswick, was ahead of Ms. Simon on election night by only 29 votes. Thinking they had lost to incumbent Republicans Jack Ciattarelli and Ms. Simon, he and his running mate, Maureen Vella of Hillsborough, conceded. But Mr. Zwicker picked up additional votes in the four counties that make up the 16th District: Mercer, Somerset, Hunterdon, and part of Middlesex. Princeton used to be in the 15th District, which has been traditionally Democrat, while Hunterdon and Somerset are Republican strongholds.

“People are asking me how this could possibly happen,” Mr. Zwicker said. “With all the big money and special interest groups, people are frustrated and feeling their voices are not being heard. This election was a grass roots effort. We didn’t have special interest money. We built up a grass roots organization.”

The fact that New Jersey set a record for the lowest voter turnout ever is not the fault of the voters, Mr. Zwicker said. “People are really upset with the way campaigns have been run. So I am beyond humbled by the fact that mine represented something bigger to many people. This is what democracy is supposed to be about. People are hugging me. They feel good. They’re saying, ‘I feel like the work I did made a difference.’ And it did — every bit of it.”

Close to 79 percent of Princeton voters cast ballots for Mr. Zwicker and Ms. Vella. “So his supporters turned out at a high percentage,” said Peter Wolanin, chairman of the Princeton Democratic Municipal Committee. “But we were hoping for some more of them.” Still, Mr. Wolanin said, the support was stronger than what was seen in recent elections for Representative Rush Holt and President Barack Obama.

Mr. Ciattarelli earned the most votes in the race for the two Assembly seats, with a total of 16,526 votes.

Mr. Zwicker ran for a seat in Congress last year, but lost. His win in the Assembly election would present Democrats with their largest majority there since 1979, giving them 52 of the 80 seats. Mr. Zwicker would become the first Democrat to hold a legislative seat in the district since it was created in 1974.

“I started thanking people before election day. I didn’t want to wait until we had the results,” Mr. Zwicker said. “I want them to know how happy I am, whether or not I win. I’m really proud.”