Tim Kaine has made his first appearance on the campaign trail as Hillary Clinton's vice presidential running mate, urging Democrats to make history by putting Ms Clinton in the White House and leaping to attack Republican presidential nominee Donald Trump's record.
Joining Ms Clinton at a rally in the battleground state of Florida on Saturday, the bilingual Mr Kaine peppered Spanish-language phrases into a speech focused heavily on introducing himself to voters unfamiliar with the low-key US senator from Virginia.
Mr Kaine criticised Mr Trump's recent suggestion that he might not honour US security commitments to NATO in Europe, and the real estate mogul's history of casino bankruptcies and founding the failed Trump University.
The former secretary of state will formally be nominated as her party's presidential candidate in the November 8 election at the Democratic convention in Philadelphia, which opens on Monday.
In choosing the soft-spoken Mr Kaine, a former Richmond mayor and Virginia governor with a long establishment resume, Ms Clinton opted for a steady hand who she hopes will offer a clear alternative to Mr Trump's volatile campaign and his Republican vice presidential choice Mike Pence.
In his speech, Mr Kaine described his childhood in Kansas City helping his father in his metal-working shop and his Catholic mission to Honduras, where he helped teenagers with carpentry and welding and they taught him Spanish.
He said in Honduras he learned the values "Fe, familia, y trabajo" - faith, family, and work.
Mr Kaine became emotional when he recalled the 2007 shooting deaths of 32 people at Virginia Tech University during his stint as governor, calling it the worst day of his life.
He promised to take on the National Rifle Association and fight for "common sense" gun control.
"I've never lost an election. I'm 8-0 and I promise you I'm not about to let that change," he said.
Ms Clinton is hoping Mr Kaine will help her appeal to independents and moderates, but some liberal groups and supporters of Ms Clinton's Democratic primary rival, US Senator Bernie Sanders, were dismayed by the choice because of Mr Kaine's past advocacy for giving the White House fast-track authority to negotiate an Asian free-trade pact.
But in a nod to party liberals, the Ms Clinton campaign said Mr Kaine will not support the still pending final version of the 12-nation Trans Pacific Partnership.
Ms Clinton passed over liberal candidates who would have generated more grassroots enthusiasm like US Senators Elizabeth Warren and Cory Booker, and Hispanic Cabinet members Julian Castro and Thomas Perez.
Ms Clinton tried to reassure party liberals about Mr Kaine, offering an extended list of his efforts on behalf of low-income workers, education and civil rights, and for expanded gun control laws and immigration reform.
Mr Trump delighted in the Democratic discord that followed Mr Kaine's pick after failing to close the fissures in the Republican Party during his own convention.