Donald Trump has said he is “a little surprised” that his Democratic rival Joe Biden chose Kamala Harris as his running mate for the US presidency.
Mr Trump told reporters at a White House briefing the California senator “was very disrespectful to Joe Biden” during the Democratic primaries.
"It’s hard to pick somebody that’s that disrespectful,” he stressed.
The current president also noted that Ms Harris ”did very poorly” when she ran for the nomination before dropping out in December.
“That’s like a poll,” he said.
Last month Mr Trump said she would be “a fine choice.”
Mr Biden, who spent eight years as president Barack Obama’s vice president, has spent months weighing up who should take up the roll in his own campaign.
He pledged in March to select a woman as his vice president, easing frustration among Democrats that the presidential race would centre on two white men in their 70s.
Mr Biden’s search was extensive, including Massachusetts Senator Elizabeth Warren and former national security adviser to Barack Obama, Susan Rice.
A woman has never served as president or vice president in the US.
Two women have been nominated as running mates on major party tickets: Democrat Geraldine Ferraro in 1984 and Republican Sarah Palin in 2008.
Their party lost in the general election.
The vice presidential pick carries increased significance this year.
If elected, Mr Biden would be 78 when he is inaugurated in January, the oldest man to ever assume the presidency.
