Mr. and Mrs. Clinton’s aides have complained all year that the former president has received uneven coverage in the news media, with attention mainly focused on flare-ups and gaffes and not on his daily successful campaigning.

"Ninety-nine point nine percent of the time, he has been the happy warrior on the campaign trail,” said Terry McAuliffe, the Clinton campaign chairman and a close confidant of Mr. Clinton’s. “The other stuff doesn’t make news.”