By Richard Cowan and Amanda Becker

WASHINGTON/ANNANDALE, Virginia (Reuters) - Hillary Clinton campaigned with potential vice presidential running-mate U.S. Senator Tim Kaine in his home state of Virginia on Thursday, testing whether the person widely seen as the "safe choice" can propel her to the White House in November.

Kaine's 16-minute introduction of the presumptive Democratic nominee in a community college gymnasium in the Washington suburb of Annandale reflected Clinton's need to reach out to Hispanic voters with her vice presidential pick. Kaine, a former missionary in Honduras who speaks Spanish, peppered his introduction with Spanish phrases and criticism of Republican Donald Trump's statements regarding Latinos.

"He trash talks Latinos - to him it doesn't matter if you are a new immigrant or you're a worker who has been here for a long time or a DREAMer or if you're a Latina governor of New Mexico or a federal judge," Kaine said to applause.

Kaine was referring to statements Trump has made about young immigrants brought to the United States by their parents, New Mexico Governor Susana Martinez and the judge overseeing a civil fraud lawsuit against Trump University.

Kaine could help Clinton check a lot of boxes in the list of requirements for a running mate.

The former civil rights lawyer is a Virginian, which could help Clinton win a battleground state in the Nov. 8 race against Trump. Such states are hotly contested because their populations can swing either to Republicans or Democrats and play a decisive role in presidential elections.

Kaine is also affable, savvy about foreign policy and has executive experience as a former governor of Virginia and a former mayor of Richmond, the state's capital.

Though the Clinton campaign is keeping the vice presidential selection process tightly under wraps, many Democrats in Washington see Kaine as the front-runner.

Some Democrats in Congress and in outside groups want to see Clinton make a more unconventional pick for her already historic run as the first female presidential nominee of a major party.

U.S. Senator Elizabeth Warren of Massachusetts, a fierce critic of Wall Street, and Julian Castro, a Latino who is the U.S. secretary of housing and urban development, are two possibilities mentioned by Democrats who want to see Clinton go with a bold choice before the Democratic convention in Philadelphia July 25-28.

Labor Secretary Tom Perez, Representative Xavier Becerra of California, U.S. Senator Sherrod Brown of Ohio and, more recently, retired Navy Admiral James Stavridis have also been mentioned as possibilities.

Asked about Kaine, Artie Blanco, a superdelegate from Nevada, said he would not be her top pick.

“Excited, no. OK with, you know, sure,” she said.

Blanco said she likes Becerra and Perez as potential picks. She said Warren “would be fantastic” and she likes Brown's stance on worker issues.

CAN HE FIRE UP VOTERS?

Thursday's event with Kaine gave Clinton an opportunity to gauge whether the 58-year-old, Harvard-educated senator would help her fire up a crowd and make for a comfortable fit on the campaign trail.

Cynthia Smith, a registered nurse from Cleveland, was at the event because her nephew is a volunteer with the campaign. She said she was not familiar with Kaine and would like to hear more from him, but at this point preferred Warren.

"I'd like to see two women," Smith said.

Clinton had lunch with Democratic senators on Capitol Hill on Thursday. After the session, the lawmakers were mostly mum.

When Senator Harry Reid of Nevada, the top Democrat, was asked by a reporter what the takeaway from the lunch was, he responded: "She's going to be president."

Clinton spoke to the senators about returning the Senate to Democratic control and about how to create jobs in all 50 U.S. states.

Some Democratic senators have been rallying around colleague Kaine, while others are holding out for a bolder pick.

Robert Menendez of New Jersey, who has served on the Senate Foreign Relations Committee with Kaine, said in a brief interview: "If you look at the totality of Tim's life and his work, I think there are elements that would bridge that divide" between progressive Democrats and more establishment Democrats who have fostered Clinton's drive for the White House.

(Reporting By Richard Cowan in Washington and Amanda Becker in Annandale; Additional reporting Luciana Lopez in New York and Patricia Zengerle in Washington; Editing by Caren Bohan and Jonathan Oatis)