Obama will help Harris in her campaign through election day, his speeches are planned in key swing states, the first of which will be Pennsylvania, a senior member of Harris' campaign told the broadcaster.
Earlier, NBC News reported that some Democrats, including a few of Harris' staff, were concerned that the vice president was not holding enough campaign events, which could cost her the election.
The US presidential election will take place on November 5. The Democratic Party will be represented by Vice President Kamala Harris, and the Republican Party by former President Donald Trump.