Miami (CNN) Tim Kaine took the stage alongside Hillary Clinton in Miami Saturday and offered his first greeting to voters as a vice presidential nominee -- in Spanish.

"Bienvenidos a todos," the Virginia senator said, a phrase that translates to "welcome to everyone."

Clinton and Kaine's first joint appearance as running mates at a campaign rally here marked the official unveiling of the Democratic ticket. The duo will face off against Republican presidential nominee Donald Trump and his running mate, Indiana Gov. Mike Pence.

Right off the bat, the contrast that the Clinton campaign will seek to highlight between Kaine and the Republican ticket during the general election was clear.

Kaine waves with Hillary Clinton during a campaign event in Annandale, Virginia, on July 14.

Kaine waves with Hillary Clinton during a campaign event in Annandale, Virginia, on July 14.

Kaine, along with World War II veterans and Senate Minority Leader Harry Reid, attend a news conference on Capitol Hill on June 9.

Kaine, along with World War II veterans and Senate Minority Leader Harry Reid, attend a news conference on Capitol Hill on June 9.

U.S. Sen. Tim Kaine, a Democrat from Virginia, questions witnesses during a Foreign Relations Committee hearing on May 26.

U.S. Sen. Tim Kaine, a Democrat from Virginia, questions witnesses during a Foreign Relations Committee hearing on May 26.

Kaine meets in April with Judge Merrick Garland, Obama's choice to replace the late Justice Antonin Scalia on the U.S. Supreme Court.

Kaine meets in April with Judge Merrick Garland, Obama's choice to replace the late Justice Antonin Scalia on the U.S. Supreme Court.

Kaine shows the photo of a 3-year-old drowned Syrian boy during a Capitol Hill news conference in 2015. Politicians and religious leaders had come together to discuss the Syrian refugee crisis.

Kaine shows the photo of a 3-year-old drowned Syrian boy during a Capitol Hill news conference in 2015. Politicians and religious leaders had come together to discuss the Syrian refugee crisis.

U.S. Vice President Joe Biden, right, administers the Oath of Office to Kaine during a mock swearing-in ceremony in 2013.

U.S. Vice President Joe Biden, right, administers the Oath of Office to Kaine during a mock swearing-in ceremony in 2013.

Kaine takes the stage with his wife and daughter Annella after winning his Senate race in 2012. Kaine has three children.

Kaine takes the stage with his wife and daughter Annella after winning his Senate race in 2012. Kaine has three children.

Kaine, as chairman of the Democratic National Committee, speaks at the University of Pennsylvania in 2010. Kaine served as the committee's chairman from January 2009 to April 2011.

Kaine, as chairman of the Democratic National Committee, speaks at the University of Pennsylvania in 2010. Kaine served as the committee's chairman from January 2009 to April 2011.

In 2008, Kaine gives a guided tour of the grounds at Fort Monroe in Hampton, Virginia.

In 2008, Kaine gives a guided tour of the grounds at Fort Monroe in Hampton, Virginia.

Obama and Kaine applaud as U.S. Sen. Jim Webb speaks at a rally in Bristow, Virginia, in 2008.

Obama and Kaine applaud as U.S. Sen. Jim Webb speaks at a rally in Bristow, Virginia, in 2008.

Cadets from the Virginia Military Institute and Virginia Tech salute as Kaine and Britain's Queen Elizabeth II enter the Virginia State Capitol in 2007.

Cadets from the Virginia Military Institute and Virginia Tech salute as Kaine and Britain's Queen Elizabeth II enter the Virginia State Capitol in 2007.

Gov. Kaine and his wife, Anne Holton, acknowledge the crowd after his inauguration in 2006.

Gov. Kaine and his wife, Anne Holton, acknowledge the crowd after his inauguration in 2006.

While running for governor, Kaine was supported by then-U.S. Sen. Barack Obama. Here, the two attend a fundraiser in Arlington, Virginia, in 2005.

While running for governor, Kaine was supported by then-U.S. Sen. Barack Obama. Here, the two attend a fundraiser in Arlington, Virginia, in 2005.

Kaine greets people at a Herndon, Virginia, homecoming parade on October 6, 2001. He was mayor of Richmond at the time and running for lieutenant governor.

Kaine greets people at a Herndon, Virginia, homecoming parade on October 6, 2001. He was mayor of Richmond at the time and running for lieutenant governor.

Presumptive Democratic presidential nominee Hillary Clinton arrives with Sen. Tim Kaine at a rally in Miami on Saturday, July 23. Clinton has selected Kaine as her running mate. Kaine has represented Virginia in the Senate since January 2013. He was governor from 2006 to 2010.

Presumptive Democratic presidential nominee Hillary Clinton arrives with Sen. Tim Kaine at a rally in Miami on Saturday, July 23. Clinton has selected Kaine as her running mate. Kaine has represented Virginia in the Senate since January 2013. He was governor from 2006 to 2010.

Speaking at Florida International University, a campus that is more than half Hispanic, Kaine described his vision for an inclusive country. Dipping in and out in Spanish several times, he drew on his experiences as mayor, governor and the time he spent helping Jesuit missionaries in Honduras to emphasize the importance of service.

"I've always believed that however you serve, what matters is whether you actually deliver results for people," Kaine said. "That's been my goal in every position I've ever held."

Kaine sheepishly acknowledged that he may not be a household name, saying: "This might be the first time you've heard my name."

But unlike the famous real estate mogul on the other side of the political aisle, Kaine argued, his heart was in the right place.

"Do you want a trash-talking president or a bridge-building president? Donald Trump trash-talks folks with disabilities. Trash-talks Mexican-Americans and Latinos," Kaine said. "With Donald Trump, it's me first!"

Then, riffing with the crowd, he added: "You're right, he doesn't trash-talk everybody -- he likes Vladimir Putin."

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Clinton introduced Kaine as someone who has shown a "lifelong commitment to social justice."

"Sen. Tim Kaine is everything Donald Trump and Mike Pence are not," Clinton said. "He is qualified to step into this job and lead on Day 1. And he is a progressive who likes to get things done."

Her introduction of Kaine was in stark contrast to Trump's first event with Pence last weekend. Trump took the stage by himself and spoke at length before turning to the topic of his new running mate. Trump and Pence, who did not know each other prior to this election, also lacked the warmth and admiration that was evident between Clinton and Kaine on stage in Miami on Saturday.

She heralded her pick as a man of faith, willing to work across the aisle and committed to furthering the progressive cause.

"In both of our families, faith wasn't just something we talked about at church on Sundays, it was a call to serve others in every way that we can," she said.

As he looked on from a stool behind Clinton, Kaine lived up to his reputation of "Mr. Nice Guy," grinning and waving to the crowd, and clearly reveling in the moment.

But Clinton warned the crowd: "Make no mistake, behind that smile, Tim also has a backbone of steel."

Pivoting to an issue that holds personal significance for Kaine, Clinton continued: "Just ask the (National Rifle Association). Over and over again he has had the courage to stand up to the gun lobby in their own backyard."

During his tenure as governor, Virginia grappled with the 2007 Virignia Tech massacre -- the country's biggest mass shooting up until that point. Fellow Virginians to this day praise the way Kaine handled the tragedy -- an episode that they say demonstrated both compassion and governing skills.

Trump offered his thoughts on Kaine via Twitter, saying: "Tim Kaine is, and always has been, owned by the banks. Bernie supporters are outraged, was their last choice. Bernie fought for nothing!"

Tim Kaine is, and always has been, owned by the banks. Bernie supporters are outraged, was their last choice. Bernie fought for nothing! — Donald J. Trump (@realDonaldTrump) July 23, 2016

He later added, "Just saw Crooked Hillary and Tim Kaine together. ISIS and our other enemies are drooling. They don't look presidential to me!"

Just saw Crooked Hillary and Tim Kaine together. ISIS and our other enemies are drooling. They don't look presidential to me! — Donald J. Trump (@realDonaldTrump) July 23, 2016

Friends and colleagues describe Kaine as steady and even-handed, often using the word "decent" to describe his character.

Politically, Democrats expect Kaine could help Clinton rally voters in the important swing state of Virginia, and that his fluency in Spanish will be a big asset as he campaigns in minority-heavy areas of the country.

Rick Ely, a Miami resident attending the event, said he believed Clinton had made a "safe choice."

"I would have preferred to see her choose Elizabeth Warren -- a more progressive agenda that way. But I certainly understand with Virginia being a swing state, the fact that he speaks fluent Spanish, is helpful," said Ely, 58.

Clinton announced her pick Friday night in a message to her supporters, ending weeks of speculation just days ahead of the Democratic National Convention in Philadelphia that's set to kick off on Monday.

But even as Clinton and her campaign methodically vetted a number of potential running mates, it was clear that Kaine was on the fast track.

Both Clinton and her husband, former President Bill Clinton, are personally fond of Kaine and believed he would be a loyal and dependable governing partner.

Aides say as Clinton deliberated over a shortlist of potentials vice presidential nominees, she continued to return to her "unshakable confidence" in his readiness for the job, as well as her personal comfort with him.

During the vetting process, Clinton was advised by her campaign chairman, John Podesta: "It needs to be someone who, whenever they walk into a room, you are glad to see them, and want to have them as part of any conversation."

Ultimately, it was Kaine that best fit that description.

Anita Goldfeld, 76, said she drove from Boca Raton to see Clinton and Kaine's first event together. Goldfeld supported Bernie Sanders during the primaries but is enthusiastically supporting Clinton -- and now Kaine -- in the general election.

"I think that he is a man who knows, who's had a lot of experience, who would be an excellent asset to Hillary," Goldfeld said.

On the criticism that Kaine is a white, male and ashe himself has put it, "boring," Goldfeld responded: "I'll take boring and knowledgeable -- I'll take a decent human being over someone like Donald Trump."