Kaine would be the first to say it, calling himself "boring"
during a recent interview.
But the Virginia senator is not without his quirks. He is one of only 20 people in U.S. history to hold office as a mayor, governor and senator. Here are seven more odds and ends you might not have known about Clinton's vice presidential pick:
The streak began more than 20 years ago, when Kaine, a lawyer in Richmond, Virginia, ran for and won a seat on the city council, according to his official Senate biography
. In 1998, he was elected its mayor, and three years later, took a step up to the state level, becoming Virginia's lieutenant governor. When the gubernatorial term of Kaine's current Senate colleague, Mark Warner, ended in 2005, Kaine defeated a Republican challenger to become the state's 70th governor.
In 2011, former Sen. Jim Webb announced he wouldn't seek re-election, opening the door to a Senate run for Kaine, who defeated another former governor, George Allen, in the 2012 election.
His father-in-law, a Republican, was an anti-segregation hero
And a former Virginia governor as well. Kaine met A. Linwood Holton Jr.'s daughter, Anne, now his wife of more than 30 years, during their time together at Harvard Law School. She currently serves as the state's education secretary.
Well before anyone knew her future husband, Anne Holton and her siblings were thrust into the center of a heated school segregation fight in Virginia when their father, who supported controversial busing laws, enrolled them at traditionally black schools in Richmond.
"As children of the governor, we could have easily continued attending our all-white schools in the West End," she said years later.
"Instead, we decided as a family to put our dad's words into action."
He plays the harmonica
No, really. Watch:
Word is that Kaine carries it with him on the campaign trail, so keep an eye out over the next few months.
He is no hero to the liberal left
While in the Senate, Kaine voted to "fast-track" the controversial Trans-Pacific Partnership and offered scattered praise for it even after Clinton made public her opposition. He has also advocated on behalf of the financial sector, signing a letter
as recently as last week urging federal regulators not to press too hard on small banks and credit unions.
The TPP question was worked out during Kaine's first meeting with Clinton, a campaign aide said. Though both have expressed support for it at various times, they have agreed that the deal in its current form is not acceptable because, among other things, it would not raise wages or strengthen national security.
He was the first senator to deliver a speech in Spanish on the chamber floor
Kaine took a year off from law school to work with Jesuit missionaries in Honduras. During that time, he became fluent in Spanish, something the Clinton campaign is now touting as they seek to build their lead over Donald Trump with Latino voters.
In 2013, Kaine became the first senator to deliver a speech entirely in Spanish on the chamber floor -- a 14-minute appeal
for immigration reform.
On religion and abortion, he's a lot like the sitting vp
Much like the current vice president, Joe Biden, Kaine is a devout Catholic who, on a personal level, opposes abortion. But he has been a loyal abortion rights supporter during his time in the Senate and now -- after a few clashes with activists during his time holding statewide office in Virginia -- owns a 100% record on the Planned Parenthood scorecard.
"While Sen. Kaine has been open about his personal reservations about abortion, he's maintained a 100% pro-choice voting record in the US Senate," the National Association for the Repeal of Abortion Laws, another abortion rights group, said in a statement Friday. "When he was governor, Tim Kaine took positions we disagreed with and actively campaigned against. We're pleased that since then, his votes and public statements have been consistently in favor of trusting women to make our own decisions."
He personally opposes the death penalty
Kaine opposes the death penalty, despite having overseen 11 executions during his time as governor of Virginia. Similar to the abortion question, he has has said that his personal beliefs come second to legal and political implications.
"I really struggled with that as governor. I have a moral position against the death penalty," he told The Washington Post
in 2012. "But I took an oath of office to uphold it. Following an oath of office is also a moral obligation."
CORRECTION: An earlier version of this story misstated the year in which Mark Warner sought election to the Senate.