Kamala Harris will name her running mate as she prepares for a tour of US battleground states aimed at turning excitement over her presidential bid into durable support that can power her to victory.

All paths to the White House run through a handful of swing states, and Harris will kick off her five-day run today in the largest -- Pennsylvania -- as she builds momentum for her showdown with Republican Donald Trump on November 5.

"At this moment, we face a choice between two visions for our nation: one focused on the future and the other on the past... This campaign is about people coming together, fueled by love of country, to fight for the best of who we are," she posted on X.

Fresh from winning enough delegate votes to secure the Democratic nomination, the country's first female, Black and South Asian vice president heads into the national convention in Chicago in two weeks in total control of her party.

In a campaign that is barely two weeks old, the 59-year-old former prosecutor has obliterated fundraising records, attracted huge crowds and dominated social media on her way to erasing the polling leads Trump had built before President Joe Biden quit the race.