US Vice President Kamala Harris accused former President Donald Trump of backing down from debating her, even though she is willing to participate.

Harris claimed to reporters that Trump previously agreed to debate on September 10. "Now appears he is backpedaling, but I'm ready, and I think the voters deserve to see the split screen that exists in this race on a debate stage and so I'm ready. Let's go on."

The first and last debate between US President Joe Biden and Donald Trump took place on June 27. Widely seen as an abysmal failure for Joe Biden, criticism about his cognitive capacity skyrocketed. 

The second debate between Biden and Trump is slated for September 10. Still, it's unclear if the latter will confront Harris, who has yet to be formally nominated by the Democratic Party.

At her first campaign speech since replacing President Joe Biden as the Democratic nominee for president, Harris attacked Donald Trump on Tuesday.

Speaking to a crowd at West Allis Central High School in a Milwaukee suburb in Wisconsin – a battleground state in the November 5 election – Harris said, "In this campaign, I promise you I will proudly put my record against his any day of the week."

"Do we want to live in a country of freedom, compassion and rule of law, or a country of chaos, fear and hate?" she asked the crowd. 

This comes as a nationwide Reuters/Ipsos poll conducted on Monday and Tuesday after Biden withdrew from the race showed Harris leading Trump 44% to 42% among registered voters.

The polls, a week ago, before Biden withdrew, showed Harris and Trump tied at 44%.

Obama set to endorse Harris soon: NBC News

Since Vice President Kamala Harris announced her presidential candidacy on Sunday, she and former President Barack Obama have been in frequent contact, engaging in multiple discussions this week, NBC News reported on Thursday citing sources.

Obama has privately expressed his complete support for Harris' campaign and is planning to endorse her in the near future, the sources added without mentioning a date.

"He has been in regular contact with her and thinks she's been off to a great start," one said.

Obama is one of the few prominent Democrats yet to endorse Harris.

One source mentioned that the former president delayed his endorsement to avoid overshadowing Biden’s Wednesday address. Another source noted that Obama and Harris wanted the endorsement to be a distinct event.

Discussions are ongoing about Obama and Harris appearing together on the campaign trail. Additionally, Obama's wife Michelle supports Harris' candidacy, according to two sources.