The Hispanic vote is crucial to Reid's campaign. Hispanics make up more than a quarter of Nevada's population, according to the U.S. Census Bureau, and comprise 14 percent of all eligible voters in Nevada this year.
De Posada served as the Republican National Committee's director of Hispanic affairs from 1989 to 1993, according to his resume. He also served as one of three directors for Americans for Border and Economic Security with former GOP Rep. Dick Armey, who now runs a leading Tea Party group, FreedomWorks. De Posada also served in the Bush administration and as an advisor to former Republican Sen. George Allen of Virginia -- who lost his reelection bid in 2006 after he was accused of using a racial slur against one of his opponent's aides.
In 1994, de Posada helped created the Hispanic Business Roundtable, which later changed its name to The Latino Coalition.
According to campaign records, De Posada also has been a longtime contributor to Republican candidates.
Reid accused Angle of backing the ad, but in a radio interview with conservative talk show host Heidi Harris today, Angle denied any link to de Posada, saying she has "absolutely nothing" to do with the ad.
"I know that there's an ad out there by an independent expenditure of some kind that has been saying that we don't want to turn out voters, but yes we do, every voter," she said. "If someone wants to spend money, they can, and you don't, you can't collaborate. You can't coordinate. You can't talk to them about it."
Hispanic voters turned out overwhelmingly in favor of Obama in 2008, and minorities in Nevada were overwhelmingly credited with helping push the Democrats to victory.
Based on analysis by Brookings Mountain West at the University of Nevada, Hispanics have a far more favorable view of the president and his party than whites do.
"I don't think it's a surprise that Nevada was targeted for this ad," said John Tuman, chair of the political science department and director of the Latin American Studies Program at the University of Nevada, Las Vegas. "If the ad depressed the Latino vote it could certainly tip the race in favor of Angle, given how close it is."
And while immigration registers as the fourth top priority for whites, it's not a top-five priority for Hispanics, according to the UNLV survey.
There is concern among Hispanics in Nevada about the lack of progress on immigration reform but the ad hasn't been viewed very favorably in the state, Tuman said.
Democrats have aggressively courted Hispanic voters through the years. In 2008, they sponsored a soccer team called "Los Democratas." They have supported labor unions dominated by Hispanics, like the Nevada culinary union.
That kind of outreach is missing from Angle's campaign, political analysts say. Instead, Angle has taken heat for ads that Hispanic groups called "race-baiting."
Angle defended images in those ads of dark-skinned men coming across a fence. To illustrate to Hispanics that ethnicities can be mixed up, Angle told Latino students last Friday that some of them could even be mistaken as Asian.