UPDATE, July 23, 6:00 p.m. EDT -- For Virginia Sen. Tim Kaine, the fall campaign began on Saturday when he gave his first speech since Hillary Clinton named him as her running mate. He opened by speaking Spanish and went on to discuss his biography and his values. 

The social media reaction was largely positive even from progressives who had been hoping Clinton would pick someone from the left wing of the party.

It's still unclear whether the fervent supporters of Clinton's defeated rival, Vermont Sen. Bernie Sanders, will back the Clinton-Kaine ticket.

Republican nominee Donald Trump also weighed in.

ORIGINAL STORY: It’s one of the last missing pieces of former Secretary of State Hillary Clinton’s campaign for the presidency: who will be her vice presidential running mate? Clinton chose Virginia Sen. Tim Kaine as her running mate Friday ahead of the start of the Democratic National Convention in Philadelphia Monday.

Clinton is scheduled to take part in an event at Florida International University in Miami Saturday starting at 12:00 p.m. EDT. A live stream of the event is available here.

Clinton supporters received a text message and email announcing the pick before the Florida rally in an effort to boost the campaign’s list of contacts, the New York Times reported. There was speculation that Clinton would delay the announcement because of the shooting in Munich, as Donald Trump did after the attack in Nice, France, but she went ahead as planned Friday evening.  

Kaine Democratic presidential candidate Hillary Clinton and Sen. Tim Kaine wave to the crowd during a campaign rally at Ernst Community Cultural Center in Annandale, Virginia, July 14, 2016. Photo: Reuters/Carlos Barria

As a popular politician from the battleground state of Virginia, Kaine could help Clinton secure a key state in the general election. The son of a welder who grew up in the Midwest, Kaine could appeal to voters that historically vote Republican. His strong positions on free trade could, however, turn off some voters, and in general he is a moderate who may not excite the Bernie Sanders wing of the Democratic party. 

Other potential running mates being vetted included Agriculture Secretary Tom Vilsack, Labor Secretary Tom Perez, Ohio Sen. Sherrod Brown and New Jersey Sen. Cory Booker. While some Democrats were hoping to see two women on the ticket, Massachusetts Sen. Elizabeth Warren said Thursday that it was not going to happen.

“I think if it were me I’d know it by now, so probably not,” Warren told late night host Stephen Colbert Thursday. “But look, she has lots of good choices, and I’m excited to see who she’ll pick.”

Florida has long been a key battleground state for candidates and Clinton’s announcement there will look to build momentum and refocus attention following the Republican National Convention in Cleveland and Republican nominee Donald Trump’s speech that targeted and lay blame on Clinton for what he views as America’s failings.

The event at Florida International University is Clinton's first public event in southern Florida since defeating Vermont Sen. Bernie Sanders in the primary. The university's student body has a large Latino population, a key demographic that could help Clinton win the Sunshine State.

Here's the full text of Clinton's announcement:

Tim is a lifelong fighter for progressive causes and one of the most qualified vice presidential candidates in our nation's history. But his credentials alone aren't why I asked him to run alongside me.

Tim’s a man of relentless optimism who believes no problem is unsolvable if you're willing to put in the work. That commitment to delivering results has stayed with him throughout his decades-long career as a public servant.

I could give you a laundry list of things he accomplished as mayor of Richmond, governor of Virginia, and in the United States Senate. But here’s what’s important: Tim has never taken a job for the glory or the title. He's the same person whether the cameras are on or off, motivated by the belief that you can make a difference in people's lives through public service.

I didn’t make this decision lightly. I’ve had the privilege of seeing two presidents and two vice presidents up close, and I wanted to pick someone who will be able to give me their best advice, look me in the eye, and tell me they disagree with me when they do. But what matters most is a simple test that’s not easy to meet: whether the person could step in at a moment’s notice and serve as president.

I have no doubt that Tim can do the job, and I want him by my side on the trail and in the White House. But we're going to need your help to get there. So join me and Tim, and let's get to work and go win this thing.