With her choice of a Midwestern governor as a running mate, Vice President Kamala Harris pushed to shore up "Blue Wall" states - Wisconsin, Michigan and Pennsylvania - that Democrats need to win to keep the White House.
Harris, the first Black woman and woman of South Asian descent to head a major party ticket, and former President Donald Trump, the Republican nominee, will also be locked in Sun Belt competition to win Georgia, Arizona, Nevada and North Carolina, an electoral map that has expanded since Biden's decision to withdraw from the race.
Tim Walz had two jump starts, the first largely unnoticed, the second underappreciated.
The first came earlier this year when the governor and the vice president visited a Planned Parenthood clinic in St. Paul. That visit underscored shared values between the two, according to people familiar with Harris' thinking. Key issues that resonated with Harris included Walz's advocacy for in vitro fertilization and child tax credits - an idea Walz has used in Minnesota.
The next key moment came July 23, two days after Biden's withdrawal, when Walz went on MSNBC's "Morning Joe" and uttered a dig at Trump and Vance that quickly went viral.