Earlier, during the initial counting of votes, Dr. Snipes’s office inadvertently mixed some 20 invalid provisional ballots in a stack of 205 otherwise valid ballots. The canvassing board ultimately accepted all the ballots, saying it would err on the side of allowing them rather than disenfranchising more than 180 valid votes.

Mr. Scott’s campaign sued for access to all the voting records, and a court found that Broward had violated public records law and the state’s Constitution.

Even before being denounced by Mr. Scott, Senator Marco Rubio and President Trump himself, Dr. Snipes’s tenure had been marred by problems, including the unlawful destruction of ballots in a congressional race that should have been kept for review, and the mishandling and misprinting of mailed-in ballots.

Democrats were highly critical of the design of the ballots in Broward County. The Nov. 6 election results showed that some 30,000 Broward voters did not make a choice in the Senate race — a significant undervote attributed to a ballot design that tucked the contest on the bottom left-hand corner of the page. That design was in violation of national guidelines that recommend not listing any race under the voter instructions. It led some Democrats to believe that the design might have cost Mr. Nelson the election.

As a result of the litany of controversies, Dr. Snipes’s exit did not surprise Broward Democrats on Sunday, even some who defended Dr. Snipes in the past but found it increasingly difficult to do so as the midterm election and recount resulted in one embarrassment after another for the county. No one, however, seemed to expect Dr. Snipes to act so quickly.

“Wow, that was fast,” Cynthia Busch, chairwoman of the county Democrats, said after learning of the resignation from a reporter on Sunday night. “People don’t have confidence in her anymore, and if that includes even those of us who have tried to be helpful over the last couple of years as best we can, that in and of itself makes it an untenable situation going into a presidential election.”

Protesters descended on the Broward elections office last week, demanding Dr. Snipes’s ouster. Pro-Trump groups went as far as to post her home address and phone number online.