Hillary Clinton introduced running mate Tim Kaine as "a progressive who likes to get things done", joining him in the crucial battleground state of Florida to help kick off next week's Democratic National Convention.
Mrs Clinton said the Virginia senator cares more about making a difference than making headlines, "everything that Donald Trump and Mike Pence are not".
Mrs Clinton offered Mr Kaine the vice-presidential spot on the Democratic ticket in a phone call on Friday night.
At the rally in Miami’s Florida International University, Mr Kaine celebrated Mrs Clinton while jabbing Mr Trump. “She doesn’t insult people. She listens to them,” he said. “What a novel concept.”
Mr Kaine (58) was long viewed as a likely choice for vice-president, a former governor of politically important Virginia and mayor of Richmond who also served as chairman of the Democratic National Committee.
He also had a particularly powerful backer: president Barack Obama, who advised Mrs Clinton's campaign during the selection process that Mr Kaine would be a strong choice.
Mr Kaine is a fluent Spanish speaker with a reputation for working with Republicans.
"Trying to count the ways I hate timkaine," Arizona Republican senator Jeff Flake wrote on Twitter. "Drawing a blank. Congrats to a good man and a good friend."
Mr Kaine was the choice over agriculture secretary Tom Vilsack, a long-time friend of the candidate and former president Bill Clinton.
The senator is viewed sceptically by some liberals in the Democratic Party, who dislike his support of free trade and Wall Street.
Notably, a campaign aide said Mr Kaine made clear “in the course of discussions” that he shares Mrs Clinton’s opposition to TPP in its current form.
Valuable asset
Mrs Clinton and Mr Kaine appeared at Florida International University in Miami. Florida is the nation's premier battleground state, and Mr Kaine is likely to be a valuable asset in Spanish-language media as the campaign appeals to Hispanic-Americans turned off by Mr Trump's harsh rhetoric about immigrants.
Mr Trump, in a text to his own supporters, said Mr Obama, Mrs Clinton and Mr Kaine were “the ultimate insiders” and implored voters to not “let Obama have a third term”.
Mr Kaine got some practice challenging Mr Trump's message when he campaigned with Mrs Clinton last week in northern Virginia, where he spoke briefly in Spanish and offered a strident assault on Mr Trump's White House credentials.
"Do you want a 'you're fired' president or a 'you're hired' president?" Mr Kaine asked in Annandale, Virginia.
“Do you want a trash-talking president or a bridge-building president?”
Agencies