President Barack Obama will not speak with Hillary Clinton about the FBI's investigation of Clinton's use of private email servers while secretary of state, the White House said on Tuesday.

"The president all along has believed that it is important for the Department of Justice to conduct their investigation free from any sort of perceived influence of the White House or anyone else in the federal government," White House spokesman Josh Earnest said.

Obama and Clinton, the presumptive Democratic presidential nominee, are traveling together on Air Force One to North Carolina on Tuesday for their first joint campaign rally for the 2016 election.