Delaying the start of a popular telenovela, Barack Obama this week gave Spanish-language television audiences in California a glossy glimpse of the prime-time advertising battle that has raged for weeks in other states.

Political observers say the campaign's move to buy a half-hour of nationwide airtime on Univision placed Latino voters on a level of critical importance alongside those who watched the English-language version of the same commercial on CBS, Fox, NBC, BET, MSNBC and TV One.

KDTV Univision 14, the national station's Bay Area affiliate, had an average audience of almost 55,000 viewers for the Wednesday night program, which made up about nine percent of all Bay Area viewers during that time, according to the Nielsen Station Index.

"We're the fastest-growing electorate in the country," said Michael Bustamante, spokesman for the Velasquez Institute, a research group based in California and Texas. "In 2004, the Democratic candidate left it up to others to sway Latino voters toward him. That's just not a strategy that will work anymore."

While polls show Latino voters generally swinging heavily toward Obama, especially in California, both campaigns have been using Spanish-language media as a critical opportunity for courting Latino support.

Sarah Palin offered a rare sit-down interview to Univision anchorman Jorge Ramos last week, revealing her first public statements on a touchy issue, illegal immigration, that the candidates have avoided speaking about in English-language settings.

John McCain was on the ground in Miami's Little Havana, trying to woo voters by making a Wednesday morning stop at Radio Mambi, popular among the Cuban exile community.

And in battleground states with significant Latino populations such as Nevada, New Mexico, Colorado, Florida and Virginia, the campaigns have aired a barrage of TV and radio ads in Spanish, some used to attack the opposing candidate's immigration stance, despite both sides having relatively similar positions.

Obama also this week began airing a commercial, called the "American Dream," that showed him directly addressing the camera and speaking in Spanish for its entirety — a first for presidential candidates.

The closest precedent may have been in 1960, when Jacqueline Kennedy made a minutelong case for her husband in Spanish, ending with "Que viva Kennedy!"

Adam Segal, director of the Hispanic Voting Project at Johns Hopkins University, said the commercial is "the icing on the cake from the Obama Hispanic outreach effort."

Segal said many states that went for Bush in the last election show an Obama lead, partially as a result of a big advantage among Latino voters. The nearly $9 million both campaigns spent on Spanish advertising in 2004 has already been vastly outspent, he said.

Some of the voting trends have been troubling for Republicans. Among Latinos in Florida, there are now about 513,000 registered Democrats, outnumbering 445,526 registered Republicans, according to a report released Wednesday by the Pew Hispanic Center, a nonpartisan research organization. Two years ago, the opposite trend was true.

Reach Matt O'Brien at 925-977-8463 or mattobrien@bayareanewsgroup.com.