Democratic presidential candidate Kamala Harris and her running mate Tim Walz held the biggest Democratic event of the election so far in Pennsylvania
Democratic presidential candidate Kamala Harris and her running mate Tim Walz held the biggest Democratic event of the election so far in Pennsylvania AFP

Kamala Harris took her breakneck presidential campaign on a tour of US election battlegrounds Wednesday as she seeks to woo a coalition of Democrats, independents and disaffected Republicans to power her to the White House.

The 59-year-old vice president has been riding a wave of excitement and an upward swing in polling in the two weeks since she replaced President Joe Biden as the Democratic standard-bearer to take on Republican Donald Trump on November 5.

Harris and her new running mate, Minnesota Governor Tim Walz, will take their campaign to Eau Claire, Wisconsin, before traveling to Detroit, Michigan, for a rally with members of the United Auto Workers union.

Just hours after Walz was announced on Tuesday, the pair held the biggest Democratic event of the election so far in front of a raucous crowd of around 10,000 in the crucial swing state of Pennsylvania.

"We are the underdogs in this race, but we have the momentum and I know exactly what we are up against," Harris told the crowd in Philadelphia.

Walz, a 60-year-old former Army National Guard officer, has been governor of staunchly Democratic Minnesota since 2019 but before that had a record as a US congressman of winning over moderate and independent voters.

Seen initially as an outsider for the VP pick, Walz enjoyed viral success in distilling Democrats' attack lines against Republicans into a relatable one-word characterization -- "weird" -- that propelled him up Harris's shortlist.

He is scheduled to appear with Harris in each of the swing states, with stops in Arizona and Nevada later in the week. Events in North Carolina and Georgia were due to be rescheduled after they were postponed due to bad weather.

Many prominent Republicans have voiced delight that Walz was chosen over the more centrist Pennsylvania governor, Josh Shapiro, an immensely popular chief executive of a state that most pundits agree will be the biggest prize in 2024.

Republicans are seeking to brand Walz as a far-left idealogue who offered benefits to undocumented migrants and tolerated rioting in the streets in 2020 after the police murder of African-American George Floyd.

House Majority Leader Steve Scalise posted on X that Walz had "let rioters burn Minneapolis to the ground in 2020."

Meanwhile the Trump campaign itself has been accusing Walz -- who retired from the National Guard in 2005 -- of having "deserted" his unit just as it was being deployed to Iraq.

It's not clear how effective the attacks will be since Trump himself acknowledged in a recent interview that "the vice president -- in terms of the election -- does not have any impact.... The choice of a vice president makes no difference."

Trump has declined to focus on Harris's own policy weaknesses, instead favoring personal attacks that have been largely ineffective in halting her rise.

Harris has a 51-48 percent lead over Trump in the latest NPR/PBS News/Marist survey and has edged ahead by 0.5 percentage points in the RealClearPolitics nationwide average of polls.

The organization had Trump three points ahead of Biden at the point when he made way for Harris, 17 days ago.

Where Trump used to be famed for his knack of defining his opponents with an incisive one-word sobriquet -- such as "Crooked" Hillary Clinton or "Lyin'" Ted Cruz -- he has struggled to come up with a nickname that will stick on Harris.

His latest taunt -- calling her "Kamabla" -- looks more like a typo than an effective insult and has left pundits scratching their heads.