US Vice President Kamala Harris and former president Donald Trump have released new television advertisements as part of a multimillion dollar battle to gain the upper hand in this year's reshaped campaign.
The Harris advertisement, which is a minute long and describes her as "fearless," serves as a highlight reel of her political career dating back to her days as a courtroom prosecutor in California.
The likely Democratic nominee, who is less well known than Trump, is racing to introduce herself to voters after being thrust to the top of the ticket when President Joe Biden ended his re-election bid a little more than a week ago.
“This campaign is about who we fight for,” Harris says in the advertisement, which is running during the Olympics, the Bachelorette, the Daily Show and other popular programs.
Her campaign said it is the first spot in a $US50 million ($A76 million) advertising push ahead of the Democratic National Convention, which starts on August 19 in Chicago.
Meanwhile, Trump is trying to define Harris in his own way.
The Republican nominee's half-minute advertisement targets her work on migration issues, dubbing her the "border czar" and blaming her for illegal crossings into the United States.
After displaying headlines about crime and drugs, the video brands Harris as "Failed. Weak. Dangerously liberal".
Border crossings hit record highs during Biden's administration - with 7 million migrants arrested for illegally crossing the US-Mexico border during his time in office, according to government data - but have dropped more recently.
Trump's campaign has so far reserved $US12.2 million in television and digital ads through the next two weeks, according to data from the media tracking firm AdImpact.
Harris will tour battleground states next week with her vice presidential candidate, two sources familiar with the planning said on Tuesday, a sign the selection process for her running mate is coming to a close.
The high-stakes decision on who will run with Harris has taken centre stage since she became the Democratic frontrunner for the November 5 election.
Harris will announce her vice presidential pick before next week's tour of states that could swing to Republicans or Democrats in November, one of the sources said.
Harris' campaign did not immediately respond to requests for comment.
The short list of candidates under consideration include Kentucky governor Andy Beshear, Pennsylvania governor Josh Shapiro, US Senator Mark Kelly of Arizona, Minnesota governor Tim Walz and Secretary of Transportation Pete Buttigieg.
On Monday, North Carolina governor Roy Cooper and Michigan governor Gretchen Whitmer both indicated they were out of the VP sweepstakes.
A handful of US states, often called battlegrounds, have decided the presidential election in recent years including Michigan, Pennsylvania and Wisconsin.
with Reuters