ORLANDO — Hillary Clinton picked Senator Tim Kaine of Virginia to be her running mate, selecting a low-profile, middle-of-the-road politician who comes with an unblemished reputation and could help Clinton expand her appeal to voters outside her liberal base, but won’t do much to excite the base itself.
The pick is widely seen as a safe choice for Clinton because the Virginia senator adds gender balance to the ticket and is, as well, a popular politician from an important swing state. It signals that Clinton’s campaign wants to peel off some of the moderate white Republicans who are uneasy with GOP presidential nominee Donald Trump’s harsh rhetoric but who have yet to warm to Clinton.
But what is safe in a normal year might not be safe in 2016. With Kaine, Clinton bypassed liberal favorites like Senator Elizabeth Warren of Massachusetts to select a career politician of a distinctly centrist stripe. She is doubling down on government experience in a year where strong outsider currents are running through the electorate. It’s a solidly bold-faced establishment ticket in an antiestablishment year that saw Trump prevail in his party and Bernie Sanders rattle Clinton with an energized insurgent campaign.
‘‘I’m thrilled to tell you this first: I’ve chosen Senator Tim Kaine as my running mate,’’ Clinton said in a text message sent to supporters Friday evening. “Welcome him to our team.”
Clinton and Kaine are set to appear together at a rally around noon Saturday in Miami.
The pick was widely expected, and came with a flurry of supportive statements. David Axelrod, a top Democratic strategist applauded the pick as a “really solid choice” for Clinton and called him a “thoroughly admirable man.”
Underscoring Kaine’s appeal to some on the right, conservative Bill Kristol, the influential editor of the Weekly Standard, complimented the Virginia senator on his Twitter feed, saying Kaine and the Republican vice presidential pick Mike Pence are both “good guys.”
“Couldn’t we reshuffle the tickets, and have a choice between Pence-Kaine and Trump-Clinton?” he asked.
Kaine reassures the party’s centrists who have been worried that Clinton tacked too far to the left during her unexpectedly tight primary challenge from populist Sanders. He is personally against abortion, though he believes women should have the right to choose. And he voted to give President Obama fast-track approval for the massive Trans-Pacific Trade accord.
But the choice of Kaine for vice president disappointed the progressive wing of the party, whose leaders had hoped that Clinton would select an ideological ally like Warren or even Labor Secretary Tom Perez.
“The mood of the country is a populist one,” said Stephanie Taylor, cofounder of the Progressive Change Campaign Committee, in a statement. “The center of gravity in the Democratic Party has shifted in a bold, populist, progressive direction — regardless of who is selected by Hillary Clinton as vice president.”
Last week, as news leaked that Kaine was a front-runner for the position, progressive groups became irate, noting that he had signed on to a letter to the Consumer Financial Protection Bureau requesting lighter regulations for some small financial services organizations.
“Our presidential ticket cannot beat the billionaire bigot by simply being not-Donald Trump,” said Charles Chamberlain, the executive director of the liberal group Democracy for America. “To win in November, our ticket needs to have an unquestionably strong record in the fight against income inequality, one of the defining issues of the 2016 election.”
Clinton’s campaign announced the news via text message several hours after she held a roundtable meeting with Orlando leaders who are still reeling from the mass shooting inspired by the Islamic State at a gay nightclub.
The announcement was evidently delayed by several hours as attention focused on an apparent terror attack in Munich. This dynamic echoed the timing surrounding the announcement of Donald Trump’s vice presidential pick, which was postponed after a terrorist attack in France.
There are other similarities between the two picks. Like Clinton, Trump filled his vice presidential slot with a well-connected party insider, Pence, Indiana’s governor. In Trump’s case, Pence is meant to bring some stability to an undisciplined ticket.
Kaine spent some of Friday in Boston raising money at the University of Massachusetts Club on Beacon Street, where he mingled with about 125 lawmakers, academics, consultants, and lawyers and was pressed on whether he was going to be Clinton’s choice.
“He said, ‘I can look you honestly in the eye and say I don’t know,’ ” said Tom Lesser, a lawyer from Northampton, who attended the event.
Kaine had other fund-raising events scheduled in Rhode Island and Nantucket Friday and Saturday. His access to big donors is another plus for Clinton, who will be able to rely on him to shoulder some of the money burden during the campaign.
Kaine, 58, also infuses the ticket with some Midwestern sensibility. He grew up in the Kansas City area and graduated from the University of Missouri before attending Harvard Law School.
His public service began in Richmond, where he was elected to the City Council in 1994 and then became mayor of that majority-minority city. There he developed a reputation of reaching out to — and winning the trust of — the African-American community, a key group that has supported Clinton. He is also conversant in Spanish.
Kaine became governor in 2006 and backed President Obama in the 2008 presidential campaign. That led him to a turn chairing the Democratic National Committee in 2009. He won his Senate seat in 2012 and serves on the Foreign Relations Committee and the Armed Services Committee.
Known for reaching across the aisle to get legislation passed, Kaine is friendly with colleagues, which caused some to draw parallels with the current vice president, Joe Biden.
“He reminds me a little bit of Biden in that he has good relationships,” said Carl Tobias, a law professor at the University of Richmond, who has worked with Kaine.
“Biden can do a lot with Senate and House members because there is a lot of mutual respect there. I think the same is true for Kaine. I think they trust him.’’
Clinton campaigned with Kaine July 14 in the northern Virginia suburbs of Washington, in a green-and-gold community college gymnasium. The pair looked comfortable together on stage, with Kaine leaning in at one point to comment in Clinton’s ear.
Kaine kicked things off by instructing the crowd on how to say “Ready for Hillary” in Spanish, then wandered into a story about his time in Honduras.
He looked comfortable but his delivery felt more pat and prefabricated than designed to fire up a rally. “Do you want a ‘You’re fired’ president or a ‘You’re hired’ president?” he asked the crowd.
His wife, Anne Holton, is Virginia’s secretary of education. The couple have two sons and a daughter.
Victoria McGrane of the Globe staff contributed to this report. Annie Linskey can be reached at firstname.lastname@example.org.