Former National Security Adviser Susan Rice on Tuesday praised presumptive Democratic nominee Joe Biden’s choice of California Sen. Kamala Harris as his running mate, describing Harris as a “great choice.” 

"I'm glad that I'm going to be able to support them and do my utmost to elect Biden-Harris and help them govern when the time comes," Rice told NBC's "Today" host Savannah Guthrie.

Rice, 55, was previously one of the top contenders to be Biden’s running mate. She said she was “happy” to be one of the candidates considered for the role.

"I am happy to have been part of this process. I'm honored and humbled to be among an extraordinary group of women who were considered,” Rice said. 

Rice shot back at the Trump campaign's attacks on Harris, calling them “baseless.” Trump has labeled Harris as “phony” and claimed without evidence that she supports “socialized medicine,” raising taxes and cutting funds for the military.

"Joe Biden is at the top of the ticket," she said. "I think they're very compatible and their positions are very close to one another. ... Let them hurl their baseless attacks. It's all they've got." 

There are several reasons why Biden chose Harris as his running mate. As Jamil Smith noted in Rolling Stone, Harris may help Black turnout while also strengthening Biden's credentials with the more liberal base of the party. The pick is especially important for Biden’s campaign, due to his advanced age and because he may only serve one presidential term.

Harris, 55, the daughter of Jamaican and Indian immigrants, is the first Black woman to be featured on a presidential ticket, making it a historic pick. As senator, she gained attention for hard questioning of Trump's attorneys general William Barr and Jeff Sessions during hearings, along with Supreme Court nominee Brett Kavanaugh. Prior to becoming California’s junior U.S. Senator in 2017, she served as the state’s attorney general for six years. Her prosecutorial experience could help the Biden campaign attack Trump’s claims that he is the “law and order” candidate.

Although Rice, whose parents are both African-American, would have also brought diversity and extensive foreign policy experience to the Biden ticket, her remarks after the 2012 attack on a U.S. diplomatic facility in Benghazi, Libya, would likely have made her a target for Republicans. Rice had served as both national security adviser and U.S. ambassador to the United Nations during the Obama era.