LAS VEGAS — Vice President Joe Biden denounced Republican presidential challenger Mitt Romney on Tuesday as a candidate with something to hide.

Biden, campaigning for President Barack Obama in the battleground of Nevada, told Hispanic leaders that Romney doesn't live up to the openness that his father represented when he ran for president 44 years ago. The vice president said Romney's father, George Romney, released 12 years of tax returns when he unsuccessfully sought the Republican nomination in 1968.

In a speech to the annual conference of the National Council of La Raza, Biden accused Romney of releasing only one year of his tax returns, "Making a lie of the old adage: Like father, like son."

Romney has released his 2010 tax return and an estimate for 2011.

Biden said Romney's father "released 12 years of tax returns because, as he said, `One year could be a fluke, perhaps done for show.'"

Biden added, to applause from the audience, that Romney "wants you to show your papers, but he won't show us his!"

The remarks underscored the Obama campaign's latest effort to portray Romney as secretive, and highlighted Romney's past hardline immigration stance.

Maria Castro, an 18-year-old recent high school graduate from Phoenix, echoed Biden, saying of Romney: "I think it's hypocritical that he is holding the immigrant community accountable, but he won't be held accountable."

La Raza is a national Latino advocacy and civil rights group. Some in the crowd said they supported Obama in 2008 and planned to do so again this year.

Ben Obregon, a board member of a Wisconsin-based migrant services group, said he thought it was fair to compare Romney filing tax returns and immigrants providing documentation.

"I certainly think they should keep up the pressure to make sure that he provides his financial records," said Obregon. "He's talking about everyone else. There's no reason he should not abide by the same rules."

Romney campaign adviser Hector Barreto accused the Obama campaign of "desperation" with an attack aimed at diverting attention from unemployment and jobs.

"They have to change the subject," Barreto said at the NCLR conference. "Jobs and the economy are the foremost issues in everyone's minds, especially Hispanics."

In a statement, Barreto and Florida state Senator Anitere Flores pointed to recent reports showing the jobless rate nationally still above 8 percent, and Barreto called the situation "precarious" for Hispanics, with almost one in three teens between the ages of 16 and 19 unable to find work.

Flores accused Obama of breaking a promise to reform immigration in his first year in office as "yet another broken promise to the Latino voters who helped elect him."

Biden's speech soared from whispered remembrances about growing up in a middle class home to warnings about what a Romney presidency would be like to an exhortation to the crowd to support Obama.

"Close your eyes and imagine what the Supreme Court will look like after four years of Governor Romney," Biden said. "Imagine what it will act like. Imagine what it will mean for civil rights, voting rights, and for so much we have fought so hard for."

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