Democratic presidential nominee Kamala Harris and her newly selected vice presidential running mate, Minnesota Governor Tim Walz, have campaigned for the first time together in Philadelphia, kicking off a multi-day tour of battleground states aimed at introducing Walz to the national stage.

Harris, the US vice president, announced her choice of Walz earlier in the day, opting for a vice presidential running mate with executive experience, military service and a track record of winning over the rural, white voters who have gravitated to former president Donald Trump over the years.

“He’s the kind of person who makes people feel like they belong and then inspires them to dream big,” Harris said while standing with Walz in Philadelphia.

"That’s the kind of vice president America deserves."

Harris, speaking before Walz, listed his titles – husband, father, teacher, coach, veteran, congressman, governor – before predicting he would earn a new one in the November 5 election as vice president of the United States.

Harris devoted much of her speech to telling the audience about Walz’s life and work, which included stints as a social studies teacher and a football coach.

“To those who know him best, Tim is more than a governor,” she said.

“We both believe in lifting people up, not knocking them down. We both know that the vast majority of us have so much more in common than what separates us. And we see in our fellow Americans neighbours, never enemies.”

In his remarks to a raucous crowd of more than 10,000 at Temple University, Walz described his upbringing in a small Nebraska town, his years serving in the Army National Guard and his prior career as a high school social studies teacher and football coach.

“It was my students who encouraged me to run for office,” he said.

“They saw in me what I was hoping to instil in them – a commitment of common good, a belief that one person can make a difference.”

Walz won the first of six terms in Congress in 2006 from a mostly rural southern Minnesota district and used the office to champion veterans issues.

Walz served 24 years in the Army National Guard, rising to command sergeant major, one of the highest enlisted ranks in the military, although he didn’t complete all the training before he retired so his rank for benefits purposes was set at master sergeant.

Kamala Harris and her newly chosen running mate Tim Walz take the stage in Philadelphia. – Reuters

Walz currently serves as co-chair of the bipartisan Council of Governors, advising the president and the Cabinet on homeland security and national defence issues. He was first appointed to the position by Trump, then later reappointed by Biden.

In his Philadelphia speech, Walz went after Republican presidential nominee Trump and his running mate, Senator JD Vance, in an early demonstration of how he will approach the traditional “attack dog” role of the vice presidential candidate despite his affable, folksy style.

“He mocks our laws, he sows chaos and division, and that’s to say nothing of his record as president,” Walz said of Trump.

“He froze in the face of the Covid crisis, he drove our economy into the ground, and make no mistake, violent crime was up under Donald Trump. That’s not even counting the crimes he committed.”

Harris’ entry into the race after President Joe Biden abandoned his re-election bid just over two weeks ago has rapidly upended the election campaign, with polls showing she has erased the lead Trump had built.

The Harris campaign said it had raised more than $20 million after the announcement of Walz as the vice presidential pick.

Pennsylvania, the site of their first rally, is seen as perhaps the most critical state in what is expected to be a close election between the Democrats and their Republican rivals.

Harris, second gentleman Doug Emhoff and Walz will spend the next five days touring critical battleground states, visiting Wisconsin and Michigan on Wednesday and Arizona and Nevada later in the week.

Second gentleman Doug Emhoff, Kamala Harris, Tim Walz and his wife Gwen wave to supporters. – Reuters

Trump, Vance call Walz ‘radical’

Walz previously coined one of Democrats’ buzziest campaign bits to date, calling Trump and his running mate Ohio Senator JD Vance “just weird”, a label that the Democratic Governors Association — of which Walz is chairman — amplified in an online post and Democrats more broadly have echoed.

On Tuesday, Walz said: “Just an observation of mind, I just have to say it. These guys are creepy and, yes, just weird.”

Walz was elected to a Republican-leaning district in the US House of Representatives in 2006 and served 12 years before being elected governor of Minnesota in 2018 and again in 2022.

He has pushed a progressive agenda that includes free school meals, goals for tackling environmental issues, tax cuts for the middle class and expanded paid leave for workers.

Trump and Vance were quick to criticise the new competition as too liberal.

“This is the most Radical Left duo in American history,” Trump wrote on his social media platform.

Vance knocked Walz for his handling of protests after George Floyd, a Black man, was killed in Minneapolis by a white police officer in 2020, with the Republican saying Walz was not assertive enough in combating the rioters.

“The biggest problem with the Tim Walz pick – it’s not Tim Walz himself. It’s what it says about Kamala Harris, that when given the opportunity she will bend the knee to the most radical elements of her party,” Vance told reporters in Philadelphia earlier in the day.

Pennsylvania Governor Josh Shapiro speaks during the rally in Philadelphia. – Reuters

Americans typically focus on the person at the top of the ticket when choosing whom to vote for, but vice presidential candidates can help or hurt their running mates based on their backgrounds, home state popularity and ability to sway important constituencies or independent voters.

“She went with her gut on this one and chose the option that won’t alienate young folks,” said Republican strategist Rina Shah.

Walz beat out Pennsylvania’s popular governor, Josh Shapiro, for the No.2 role. Shapiro had faced sharp criticism from the left, especially progressive groups and pro-Palestinian activists, over his support for Israel and his handling of college protests sparked by the war in Gaza.

Harris, the first Black woman and person of South Asian descent to lead a major party ticket, initially considered nearly a dozen candidates before zeroing in on a handful of serious contenders.

Trump has focused much of his campaign on appealing to men, emphasising a need for strength in national leadership and even featuring the wrestler Hulk Hogan on the final night of the Republican National Convention. Harris’ finalists – all white men – marked an acknowledgement of the Democrats' need to at least try to win over some of that demographic.

It was Harris' biggest decision yet as the Democratic nominee and she went with a broadly palatable choice — someone who says politics should have more joy and who deflects dark and foreboding rhetoric from Republicans with a lighter touch – a strategy that the campaign has been increasingly turning to since Harris took over the top spot.

Shapiro delivered a fiery speech at the Tuesday evening rally in his home state, attacking Republicans and promising to “work my tail off” to get Harris elected. He also offered a strong endorsement of Walz, telling the crowd that he is an “outstanding governor” and a “great patriot”.

 Tim Walz speaks during a campaign rally with Kamala Harris in Philadelphia. – Reuters

Takeaways from a Harris-Walz ticket

The stage is set for an election that was unimaginable mere weeks ago when President Joe Biden was atop the Democratic ticket. Now Vice President Kamala Harris has tapped Minnesota Governor Tim Walz as her running mate to take on Republican Donald Trump and his No.2, Ohio Senator JD Vance.

How Walz might help – or hurt – Harris’s chances

Opting for the Minnesota governor immediately calms the Democratic Party’s left wing, which was worried that another contender, Pennsylvania Governor Josh Shapiro, might have pushed the party closer to Israel and disheartened Arab American and younger voters. Some in Harris’s inner circle saw Walz as a do-no-harm choice who can keep the party unified heading into the Democratic National Convention opening in Chicago on August 19.

Progressives are already celebrating Walz’s ability to deliver an unapologetically populist message in the style of a Midwestern dad who recalls the social studies teacher and football coach he once was.

Activists who for months have followed Biden around the country to protest his full-throated support for Israel in its war with Hamas in Gaza are hopeful that Walz will help Harris take a more nuanced approach than someone like Shapiro.

But some critics will point to 2016, when the only other woman to be nominated for president, Hillary Clinton, picked a mild-mannered dad with centrist views and a modest national profile – Senator Tim Kaine of Virginia. That ticket lost to Trump.

Exciting each side’s most loyal supporters

Neither vice presidential pick seems to do much to build out his party’s coalition – a sign that both campaigns view this election as about boosting turnout from their existing bases.

Just as Walz hails from the solidly Democratic state of Minnesota, Vance comes from the safely Republican state of Ohio. There is a bet that each choice can radiate Midwestern appeal to the key “blue wall” states of Michigan, Pennsylvania and Wisconsin simply by dint of geographical proximity.

Harris allies have stressed Walz’s ability to appeal to rural voters, although his 2022 re-election as governor roughly matched the margins of Joe Biden’s 2020 presidential win in Minnesota. Trump won 6 in 10 rural and small town voters nationwide in 2020, according to AP VoteCast.

The Trump campaign was quick to try to connect Walz to its characterisations of Harris as a California liberal, saying his support for gun control and teachers unions make him a “West Coast wannabe”.

Vance, for his part, comes from a state that has twice backed Trump by 8 percentage points. Just like the former president with his book Trump: The Art of the Deal, Vance achieved national recognition with his memoir, Hillbilly Elegy. Vance has mainly played to cultural and policy issues favoured by strict adherents of Trump’s “Make America Great Again” movement such as cutting military support for Ukraine.

Vance offering battleground counter-programming to Walz

Vance is set to follow an overlapping itinerary to Harris and Walz over the next two days, including stops in the battleground states of Pennsylvania, Michigan and Wisconsin. His role is to attack the Biden administration’s policies and tear down Harris’s record on the economy, public safety and immigration.

Vance got out ahead of the Democrats in Philadelphia on Tuesday, holding an event hours before Harris was to formally introduce her new running mate at a rally. He said during his Philadelphia stop that “I absolutely want to debate Tim Walz”, but not until after the Democratic convention.

Harris’ team seemed to be happy to have Vance making the contrast with the Democrats.

“We appreciate JD Vance providing voters in battleground states exactly the split-screen that defines the choice this November,” said Harris campaign spokesman Charles Lutvak.

Plenty of drama still to come

Walz’s selection settled one big question mark among Democrats, but plenty of major challenges remain for the final months of a race already defined by its unexpected twists and turns.

There is the prospect of a wider war in the Middle East, the possibility of a rate cut by the Federal Reserve that might calm global financial markets and questions about whether Trump and Harris will actually square off in a September debate that was set before Biden bowed out of the race.

No matter what happens, the conventional narratives of a presidential campaign have already had seemingly brief shelf lives. Voters over the past few weeks have dealt with Biden’s disastrous performance in the June 27 debate against Trump, a brazen assassination attempt on Trump, Biden’s exit from the race and Harris’s quick ascendance among Democrats.

Now that both tickets are settled, a reckoning will take place over positions, and small differences can matter to voters who on the margin could decide a narrow election. Global events can upend talking points in ways that are hard to predict. The 2008 campaign intensified with that year’s financial crisis, while the persistence of the coronavirus shaped 2020.

If there are any lessons from this year, it’s that election year surprises are no longer reserved for October.