His previous work had been as an assistant on more limited redistricting cases in Georgia, Virginia and Utah. Last year, however, Mr. Cervas was hired for a statewide project, as part of a redistricting commission in Pennsylvania, where the chairman, Mark Nordenberg, said he proved invaluable as a redistricting specialist, as well as having “a deep knowledge of the law” and, of course, “technical, mapping skills.”

“He approached everything we did in a fair and nonpartisan fashion,” said Mr. Nordenberg, the former chancellor of the University of Pittsburgh, noting he “would hire him again if I had the opportunity.”

That said, Mr. Cervas had never been a special master, particularly on such a tight deadline: about five weeks to deliver the final maps, including and incorporating revisions. He worked with several assistants and solicited comments from the public, both online and in a single, in-person hearing in Steuben County, about 275 miles from New York City.

And while the remoteness of that location made court appearances cumbersome, some anti-gerrymandering advocates made the trip to voice support for the new maps.

“I have to say I was pleasantly surprised,” said Jerry Vattamala, the director of the Democracy Program at the Asian American Legal Defense and Education Fund, which was part of a coalition lobbying for more representation for people of color in New York City, adding that Mr. Cervas seemed responsive to the thousands of comments he received. “So the six-hour drive, I guess, was worth it.”

In some ways, Mr. Cervas seems destined to have played an outsize role in Democratic woe: He was born, outside Pittsburgh, on Election Day in 1984, when Ronald Reagan humiliated the party’s nominee, Walter Mondale, winning a second term. His upbringing — in two swing states — was working-class: His father was a field service representative for Whittle Communications, his mother worked at Kmart.

The family moved to Las Vegas in the early 1990s, and Mr. Cervas became interested in politics, eventually studying the topic at the University of Nevada-Las Vegas and graduating with a degree in political science. He supported himself by working in a movie theater at a casino and eventually tending bar, a job he said helped him learn how to listen to divergent opinions.