As the scheming ex-model-turned-bimbo on the make Gabrielle Solis, Eva Longoria clacks her way along Wisteria Lane in Desperate Housewives with a keen eye on her husband's chequebook and the gardener's pecs. Beyond the plastic shrubs on Disney's Universal Studios lot, however, Longoria is slowly emerging as a siren voice of the American left. And with the way opinion polls are going, this energetic campaigner is suddenly at the heart of Democrat hopes for winning and retaining power.
Longoria is that rare thing in America - a Latina liberal. That she is famous and fabulous helps, but her heritage is key. There are 41 million Hispanic Americans in the US, the largest minority in the country, but less than half voted in 2004. Those who did, tended to vote Republican, won over by Karl Rove's strategy of wooing Latino church leaders. This still leaves a pool of some 20 million potential voters: and non-voting Latinos tend to be the poorest - usually farmworkers with little legal protection and no healthcare. The past two presidential elections were won by a margin of less than 2 per cent, so those votes could have changed the outcome.
Pre-election polls show leading Latino organisations deserting the Republicans, mainly on the grounds of the party's immigrant bashing (specifically, the bill authorising the fence along the Mexican border and making it unlawful for churches and charities to help illegal immigrants). At the same time, the Democrats' silence on immigration issues could mean those votes simply vanish. Few public figures have spoken out for immigrants. When millions of Latinos took to the streets to protest the bill in May, the Washington Post noted the absence of Sean Penn, Tim Robbins, Susan Sarandon, Barbra Streisand and George Clooney.
Hollywood's exception was Longoria. She was on the road promoting her big-screen thriller The Sentinel at the time, and backed the protests in interviews, branding the bill "insulting".
"It happened before in the Thirties where we had a huge deportation of Mexicans due to a racist policy," she said. "They leave their countries to come here and make three bucks an hour with no health insurance and no recognition as a citizen, and I'm going to tell them that they have to learn English? It's important to hold on to something."
I meet her on one of her rare days off. She's tiny and in need of coffee. "I hate make-up. I hate hair," she grumbles. "You're lucky I'm not in my pyjamas right now." She's frustrated that she has been unable to get out on the stump as she did in 2004, when she campaigned for John Kerry, acting as his Hispanic ambassador. "I went out and got Latinos to vote, but they voted for the wrong person," she shrugs. "They voted religion."
In campaigning for Kerry, she was hardly alone. Hollywood is packed with limousine liberals espousing a variety of fashionable causes. Whether it's wearing red for Africa, eschewing fur or adopting a third world orphan, there's a healthy link between celebs with a heart and cute photo opportunities. Longoria, however, has immersed herself in old-school issues such as trade-union rights, healthcare for farmworkers and defending immigration.
"I've always been active around Latino civil rights," she explains. "Where I come from in Texas, I was seeing immigrant workers come to do the jobs no Americans would. You have these people who have left their families and their churches and their communities to come to America to make $2 an hour and send half back home. They should be granted rights - health benefits, a break during the day . . . We actually have children working in the fields picking oranges for Americans."
Last year, she set up a production company to work on her political films. Its first project is a documentary - put together with the National Council of La Raza (NCLR), the largest Latino civil-rights organisation in the US, and the United Farm Workers union - showing a day in the life of an immigrant worker. Longoria spent time working in the fields with farmhands to research the film.
"It's horrendous," she says, still clearly shocked at what she saw. "They're being treated like slaves. We're actually having to bring an anti-slavery lawsuit against orange growers in Florida. It's 2006 and we have to use anti-slavery laws."
Her next film is the life story of Dolores Huerta, a close associate of the union leader César Chávez. "She was really the backbone of the Latino labour movement in America. She is probably the last living civil-rights icon. She was behind the great boycotts [such as] the lettuce boycott, and everything the United Farm Workers union has done. She is 75 now . . . Her story is amazing. I would love to play her."
Off screen, Longoria has visited Congress to speak in support of Padres, a charity that provides translators to Spanish-speaking parents of Hispanic children with cancer. "Latinos have the highest death rate in children with cancer," she says. "Childhood cancer is highly curable, so there is no reason for kids to be dying for something as simple as a language barrier."
She says there has been no negative backlash from her campaigning - but her immigration comments attracted abuse from right-wing commentators such as Erik Rush. On a Republican website, he described her views as "the biggest pack of ignorant, specious, pro-illegal immigration swill I've heard to date".
There was a surreal undertone to some of the attacks, with bloggers ranting at her politics while drooling over her bikini-clad form on the cover of US Maxim. Adding a bizarre twist, the publishers blew up a copy of the picture until it was large enough to be visible from outer space and spread it across the desert outside Las Vegas to celebrate the title's 100th issue.
But the hapless Maxim writer sent to seek her views on vibrators and adultery - journalists rarely ask her about anything else - received a lecture about the slavery lawsuits of the Mexican American Legal Defence and Educational Fund in Florida. The Q&A shows the journalist responding in monosyllables, miserably watching his "red-hot Eva" headline drift out of sight.
Longoria still isn't sure the Latino vote can be swung for 2006. "We tend to be a very conservative culture," she says wearily. "We live by religion, we live by our families. We need to unite. We are a competitive culture within ourselves. Puerto Ricans against Mexicans against Dominicans. If you have many voices, you just make noise."
She will not be drawn on her political ambitions. Once Desperate Housewives has finished, she'd like to focus on film - both acting and producing projects such as the Huerta biopic. Most of her activism will be directed though the NCLR.
"The mission of the NCLR is far more important than any personal recognition," she says. "The best thing I can do is ensure positive portrayals of Latinos in the media. We're in this big debate about the future of our immigration laws, and it is coloured by the negative portrayals of Latinos on television. We're 14 per cent of the population, but we make up 5 per cent of the characters on TV."
And does she see Gabrielle as part of that positive portrayal? She pauses and grins. "It's an amazing role because we're the richest people on the block and we're Latinos, which is really uncommon." Then she gives a full-throated Eva chuckle. "And we have a white gardener . . ."
"Desperate Housewives" resumes on Channel 4 from January