LAS VEGAS — Unable to shake what has become a lingering distraction for her campaign, Hillary Clinton on Thursday played down a report from the State Department’s inspector general that criticized her use of a private email server while she was secretary of state.

In an interview with ABC News, Mrs. Clinton repeated her concession that using the private email server was a mistake. But she suggested that voters had more important issues to consider when making up their minds between her and the presumptive Republican presidential nominee, Donald J. Trump.

“As I’ve said many times, if I could go back, I would do it differently,” Mrs. Clinton said. “I know people have concerns about this. I understand that. But I think voters are going to be looking at the full picture of what I have to offer, my life and my service, and the full threat that Donald Trump offers our country.”