WASHINGTON — In the first Democratic presidential debate, Bernie Sanders dismissed concerns about Hillary Clinton’s use of a private e-mail account and server while she served as secretary of state, saying Americans were tired of talking about her “damn e-mails.”

As the candidates take the stage for their last debate of the year, will Clinton return the favor?

Friday’s revelations that four members of Sanders’ campaign staff improperly accessed voter information compiled by Clinton’s campaign shook up what had been a relatively civil race. It is a development that has the potential to transform a sleepy Saturday debate into something far livelier.

The question facing Clinton is how forcefully to confront Sanders about the actions of his campaign staff and whether to defend the reaction of the Democratic National Committee, which cut off Sanders’ access to the party’s voter database after learning of the breach. The DNC said it would restore access Saturday.

At the center of the dispute is an extensive trove of voter information maintained by the DNC. The campaigns are able to add their own information to that database, information they use to target voters and anticipate what issues might motivate them to cast ballots.

In Clinton’s case, campaign manager Robby Mook said the information stored in the database and illicitly reviewed by Sanders’ team included “fundamental parts of our strategy.” Experts said the Sanders campaign employees who accessed the Clinton voter information without authorization appear to have broken the law.

“Our data was stolen,” Mook said. “The data that they reached in and took from our campaign is effectively the strategic road map in those states.”

It was an allegation rejected out of hand by Sanders’ campaign, which filed a federal lawsuit against the DNC seeking to regain access to the voter records. The lawsuit argued the DNC’s actions have caused Sanders’ campaign “injury and financial losses.”

“It’s outrageous to suggest that our campaign `stole’ any data,” said Sanders spokesman Michael Briggs. “What is true is the data we collected and need to run a winning campaign is now being stolen from us by a DNC dominated by Clinton people.”

Early Saturday, the DNC said the Sanders campaign had complied with its request for information about the incident.