When Harris took the podium, she thanked Cheney for her courage and said it was a "profound honor" to have her support.

"We may not see eye-to-eye on every issue, and we are going to get back to a healthy two-party system, I am sure of that, where we will have vigorous debates," Harris said to Cheney.

Harris talked about her commitment to the Constitution and to upholding democracy — an issue that is a deciding factor for a majority of voters this year, polling from NPR News/PBS/Marist shows.

"I believe that anyone who recklessly tramples on our democratic values as Donald Trump has, anyone who is actively and violently obstructed the will of the people and the peaceful transfer of power as Donald Trump has, anyone who has called for, I quote, 'termination of the Constitution of the United States' as Donald Trump has, must never again stand behind the seal of the president of the United States," Harris said.

In recent weeks, Harris' campaign has worked to highlight support from more than 200 prominent Republicans as she works in swing states like Wisconsin to win over more independents and Republicans disaffected with Trump.

In addition to Cheney, her father, former Vice President Dick Cheney, has also said he will vote for Harris.

Dick Cheney said in a statement last month that Trump "can never be trusted with power again" because he “tried to steal the last election using lies and violence to keep himself in power after the voters had rejected him.”