Clinton, Kaine Ticket Debuts in Miami Ahead of DNC

Clinton campaigns with Kaine for first time since naming him as her VP pick.

The two walked arm and arm onto the stage at Florida International University before a crowd of more than 5,000, making it one of the largest rallies to date for Clinton's campaign.

Clinton took the microphone first, giving some of the reasons that she picked the Virginia senator. She announced him as her running mate via tweet Friday night.

"As I have said, the most important qualification when you are trying to make this really big choice is, 'Can this person step up to be president?' Well, at every stage of Tim's career, the people that know him best have voted to give him a promotion," Clinton said, referring to Kaine's career progression from mayor of Richmond, Virginia, to governor to U.S. senator.

Clinton called Kaine at 7:32 p.m. Friday to offer him the position. Kaine was at a fundraiser in Newport, Rhode Island. Shortly after he got the call, Kaine left the fundraiser. His former staffers and friends began celebrating in Richmond as the news was revealed.

A Clinton campaign official said that during her decision-making process, Clinton kept reiterating her belief that Kaine could do the job of vice president. At the rally today at Florida International University, Clinton made the same point.

He is "a leader who cares more about making a difference than making headlines," Clinton said.

She also described Kaine as a fighter.

"Make no mistake. Behind that smile, Tim also has a backbone of steel. Just ask the NRA," said Clinton in reference to Kaine's fights against the gun-lobbying group

Kaine showed some of his fighting spirit in his criticism of Donald Trump in the speech.

"Do you want a 'you're fired' president or a 'you're hired' president?" Kaine said to the crowd.

He was alluding to the "you're fired" line from Trump's former reality show, "The Apprentice," and he also referred to Trump's business bankruptcies.

Clinton, said Kaine, would be a "you're hired" president, such as through policies to build public infrastructure projects and raise the minimum wage.

Kaine also introduced himself to the crowd by telling a little of his biography.

"Vice president was never a job I thought about growing up in Kansas," he said in a speech interspersed with Spanish, in which he is fluent.

Kaine also touched on some of Clinton's major talking points: "We are going to make the American economy work for everyone, not just those at the top," he said.

The senator and former Virginia governor was long viewed by pundits as one of the most qualified of the contenders on Clinton's list of VP candidates. Although he endorsed President Obama in 2008, he was an early supporter of Clinton's 2016 presidential bid.