The former president’s running mate, the Ohio senator JD Vance, has been dispatched to respond to Ms Harris’s VP selection, starting with a campaign stop of his own in Philadelphia on Tuesday.
Ms Harris’ selection process has exposed some divisions within the Democratic Party.
Given Ms Harris’s lightning-fast ascension to becoming the party’s presumptive nominee, the hunt for a vice presidential candidate has played out as a proxy primary with acrimonious lobbying campaigns for and against the candidates.
Mr Shapiro, the bookies’ favourite, has been championed by moderates and is popular in his home state of Pennsylvania, whose 19 electoral votes make it a must-win state for both Ms Harris and Mr Trump.
However, he has faced resistance from progressives, who have cited concerns over his staunch support for Israel.
Mr Walz, 60, has become the favourite candidate of the party’s Left flank. A former teacher and officer in the National Guard, he served as both a football coach and faculty adviser for the Gay-Straight Alliance student organisation during his two-decade teaching career.
He was elected to the House of Representatives in 2006 in a Republican-leaning district and is currently serving his second term as governor of Minnesota, where he has delivered on a string of progressive priorities such as free school meals and expanding paid leave.
Ms Harris’s reported short-list of running mates has solely consisted of white men with a record of winning over rural, white or independent voters.
In addition to Mr Shapiro, Mr Walz and Mr Kelly, potential contenders include transportation secretary Pete Buttigieg, Kentucky governor Andy Beshear and Illinois governor JB Pritzker.
The candidates will be informed of Ms Harris’s decision on Monday night or Tuesday morning, according to Reuters.
