By Jill Serjeant

LOS ANGELES (Reuters) - "Veep" star Julia Louis-Dreyfus won her fifth straight Emmy on Sunday for her role in the satirical White House comedy on a night when politics played large in the midst of an extraordinary 2016 U.S. election campaign.

Veteran Jeffrey Tambor won best comedy actor for a second time for his role as a father who transitions to a woman in Amazon's ground-breaking "Transparent."

Louis-Dreyfus, who plays the vainglorious U.S. president Selina Meyer on HBO's "Veep", apologized for what she called "the current political climate."

"I think that 'Veep' has torn down the wall between comedy and politics. Our show started out as a political satire but it now feels like a sobering documentary," she said while accepting her award.

As Americans prepare to vote in November for a new president, "Veep" is also expected to win the coveted comedy series category, which is announced at the end of Sunday's three-hour ceremony.

Indian-American Aziz Ansari shared his first Emmy for writing his new Netflix comedy "Master of None."

"Saturday Night Live" comedian Kate McKinnon, who plays Democratic U.S. presidential nominee Hillary Clinton, won supporting comedy actress, while Louie Anderson was named best supporting actor for playing the wholesome mother of Zach Galifianakis' quirky clown in the FX comedy "Baskets."

Host Jimmy Kimmel opened Sunday's show with a string of jokes about Republican presidential contender and former "Celebrity Apprentice" host Donald Trump, and former football star O.J. Simpson, whose 1995 double murder trial and acquittal was dramatized in "The People v. O.J. Simpson," which is expected to be a big winner on Sunday.

"If Donald Trump gets elected and he builds that wall, the first person we are throwing over it is Mark Burnett," quipped Kimmel, addressing Burnett, the British producer who created "Celebrity Apprentice."

FX's "The People v O.J. Simpson: American Crime Story," went into Sunday's show with 22 nominations, including multiple acting nods, writing, and best limited series.

Nominee Sarah Paulson, who played prosecutor Marcia Clark in the show, was teased for bringing Clark along with her to the Emmys.

"Are you rooting for O.J. to win this time?," Kimmel asked Clark.

Other early winners included "Saturday Night Live" comedian Kate McKinnon, who plays Democratic U.S. presidential nominee Hillary Clinton, who won for supporting comedy actress. Louie Anderson was named best supporting actor for playing the wholesome mother of Zach Galifianakis' quirky clown in the FX comedy "Baskets."

This year's Emmys are among the most diverse ever with people of color nominated in every lead acting category.

Rami Malek, 35, who is of Egyptian descent, is a front-runner for his first Emmy for his lead role as a socially awkward computer hacker in USA Network's "Mr. Robot

Awards pundits say the Golden Globe-winning show, beloved by critics despite an audience of only about one million, could also cause an upset in the drama series race where it is competing against HBO's medieval fantasy "Game of Thrones," which dominates with 23 nominations.

(Additional reporting by Piya Sinha-Roy; Editing by Sandra Maler and Mary Milliken)