“They were aggressive in a way without coming across as too thirsty or too aggressive,” said Ken Martin, the chairman of the Minnesota Democratic-Farmer-Labor Party. “They definitely were out there pushing hard, but doing it in a way that didn’t alienate Kamala Harris or her team.”
This account of Mr. Walz’s rise is based on interviews with more than a dozen Democratic officials, activists and donors who are close to the Harris campaign or to Mr. Walz.
The Walz aides understood the challenge they faced: In a party that valued diversity, the governor was an older, white former high school football coach who exuded Midwestern dad vibes. But they also knew that making him go viral would take effort and skill. He could not look too media-hungry and needed to rely on his authenticity to stand out in a party dominated by more polished performers.
Even the moment that appeared to suddenly catapult him into the hearts of Democratic donors and voters had been months in coming. Mr. Walz unveiled his attack that former President Donald J. Trump was “weird” in February, long before Mr. Biden exited the race.
He repeated the line in speeches and TV appearances, but the epithet caught fire at just the right time: when Ms. Harris was looking for a running mate and Democratic voters were paying fresh attention to a race they had wanted to ignore. Mr. Walz’s words became a refrain for Democrats eager to take down a man who had been built up to supervillain proportions by the Biden campaign.
“These ideas that they’re putting out there, they are weird as hell,” Mr. Walz said at a rally on Wednesday night in Michigan.
The media blitz had some Democratic operatives describing themselves as “Walz-pilled” — sudden converts to his cause. At the same time, the Trump campaign and some progressive activists focused on undercutting Gov. Josh Shapiro of Pennsylvania. Some Democratic officials and strategists circulated rumors of personal misconduct about other candidates, largely leaving Mr. Walz unscathed.
But Mr. Walz also relied on a skill he had refined over a career in the classroom and a conservative congressional district: being pleasantly agreeable.
When he was asked to defend Mr. Biden in the news media, Mr. Walz said yes. When he was asked to lead the Democratic National Convention’s rules committee, he said yes. And when he was asked to speak at party dinners, raise money for Democratic campaigns or help colleagues, Mr. Walz said yes — and distributed his cellphone number to nearly anyone who wanted to follow up.
Some of his actions amounted to the political equivalent of shoveling the neighbor’s driveway in the middle of a Minnesota snowstorm. Since December, he had led the Democratic Governors Association, which required him to vouch for Mr. Biden during a period when the president’s misstatements and sinking approval ratings needed a lot of explaining.
In January, the weekend before the Iowa caucuses — in which Mr. Biden did not compete — Mr. Walz agreed to drive for hours through subzero temperatures and a foot of snow to make the president’s case early Sunday on NBC’s “Meet the Press.”
It was that perceived generosity that most impressed Ms. Harris and her team. Her advisers had begun by considering nine candidates — in addition to the widely reported final six, Gov. Michelle Lujan Grisham of New Mexico, Gov. Wes Moore of Maryland and Gina Raimondo, the secretary of commerce, were vetted — and Mr. Walz was not perceived as a front-runner.
But the Harris team liked his loyalty. Unlike Mr. Shapiro, who wanted to know how the relationship would work if he were on the ticket, Mr. Walz volunteered that he would do whatever Ms. Harris wanted and minimized his political ambitions, according to two people familiar with the selection process.
Ms. Harris saw him as a trustworthy partner who was not looking to promote himself at her expense. Her aides were particularly taken by Mr. Walz’s admission during the vetting process that he did not use a teleprompter. He had to practice with the machine before their first rally in Philadelphia.
When Marty Walsh, an informal Harris adviser and former labor secretary who was helping with vice-presidential vetting, confronted Mr. Walz with the details of his drunk-driving arrest in 1995, the governor said he had no excuses. He had learned from the experience, he said, and had not drunk in decades.
That openness vaulted him to the top of the Harris team’s list.
But his long relationships, dating to his first campaign for office in 2006, also paid dividends. His home-state senators, Amy Klobuchar and Tina Smith, promoted him in the news media and in private discussions with people close to the Harris campaign. Mr. Walz himself urged his former House colleagues to vouch for him, just in case anybody asked.
He also did some of the work on his own. Out of the blue recently, he called the Rev. Al Sharpton, the civil rights leader and media figure — and occasional informal adviser to Ms. Harris — just to check in, Mr. Sharpton said.
Mr. Walz also had help from some other longtime fans.
About a week before Mr. Biden ended his campaign, Jane Kleeb, the chair of the Nebraska Democratic Party, was traveling in Cambodia when she realized that the party would soon need a new running mate. The opportunity to elevate a fellow Midwesterner and Nebraska native struck her as a chance not to be missed. For years, she had been friends with Mr. Walz, a regular speaker at fund-raisers for Nebraska Democrats.
So along with some progressive allies in the Midwest, Ms. Kleeb helped draft a document promoting his strengths as a running mate. When Mr. Biden dropped out, the document circulated widely, helping lift Mr. Walz’s profile.
Its 10 pages included a brief biography, details on his legislative record, links to positive news coverage and flattering photographs, including one showing children hugging him during the signing of a bill creating a free school-lunch program for all Minnesota students.
Ms. Kleeb was in contact with Mr. Walz’s chief of staff, who she said was appreciative but did not provide direction — or suggest that the group should stop.
“This was the one moment where we could get someone who understands rural populist culture and believes in state parties,” Ms. Kleeb said. “We couldn’t ask for more.”
Last year, Ms. Kleeb had introduced Mr. Walz to the gun-control activist David Hogg, who bombarded aides to Ms. Harris with texts and old video clips he had found of Mr. Walz — to the point that Mr. Hogg said the Harris campaign once gently told him that they “got it.”
At the same time, Mr. Walz began his whirlwind media tour, doing five TV interviews on four networks two days after Mr. Biden dropped out. By the end of the week, he had done seven more, along with long interviews on influential liberal podcasts.
Those appearances helped cultivate liberal donors, many of whom had known little about Mr. Walz but ended up evangelists for him.
“Walz wasn’t even on my radar when I was throwing in suggestions,” Reid Hoffman, a major Democratic donor, told an audience of venture capitalists on Wednesday.
Doran Schrantz, a Walz-allied operative in Minnesota who helped write the document that Ms. Kleeb circulated, described a close-knit network of strategists in the state — many with ties to organized labor — pushing Mr. Walz’s case.
Ms. Schrantz summed up the group’s thinking: “What the hell — let’s do this for Tim Walz.”
On Monday night, Donna Brazile, a Democratic strategist who worked with Mr. Walz on the convention’s rules committee, began to sense that he might be chosen.
As she walked her dog, Ms. Brazile embarked on her own informal vetting process, beginning by calling Keith Ellison, the Minnesota attorney general, who was in Peru. Mr. Ellison suggested that she contact other top Minnesota officials, including Black leaders who had worked with Mr. Walz.
Ms. Brazile wrote down her findings on a pink notepad and sent them to friends involved in vetting the potential candidates — offering a late-night endorsement in the final moments.
“I don’t know where you all are, but Gov. Tim Walz, everybody gives him thumbs up,” she recounted telling them. “By the way, I didn’t get that 100 percent thumbs up for any of the other candidates.”
Reid J. Epstein covers campaigns and elections from Washington. Before joining The Times in 2019, he worked at The Wall Street Journal, Politico, Newsday and The Milwaukee Journal Sentinel. More about Reid J. Epstein
Lisa Lerer is a national political reporter for The Times, based in New York. She has covered American politics for nearly two decades. More about Lisa Lerer
Shane Goldmacher is a national political correspondent, covering the 2024 campaign and the major developments, trends and forces shaping American politics. He can be reached at shane.goldmacher@nytimes.com. More about Shane Goldmacher
Theodore Schleifer writes about campaign finance and the influence of billionaires in American politics. More about Theodore Schleifer