Los Angeles

TRACEY ULLMAN did not become an American citizen merely so she could make fun of the residents of these United States.

She had already done that, of course, beginning with “The Tracey Ullman Show,” a sketch comedy and variety show on the fledgling Fox network from 1987 to 1990, and then on “Tracey Takes On ...” on HBO beginning in 1996. Add “The Trailer Tales” (2003) and “Tracey Ullman: Live and Exposed” (2005), again on HBO, and it is clear that she has shown little reluctance to skewer the personal foibles of Americans large and small.

But Ms. Ullman, 48, who was born in England and moved here more than 20 years ago, says that passing her civics test and taking her Oath of Allegiance in 2006 “has released me psychologically to say that bit more about the people I impersonate.”

That is evident in her new series, “Tracey Ullman’s State of the Union,” which begins Sunday on Showtime. In the form of, among other characters, Doris Basham, the retiree who smuggles prescription drugs into the United States from Canada; Mary Ann Lefrak, the country’s oldest expectant mother; and Gretchen Pincus, the serial monogamist who marries residents of Death Row, Ms. Ullman probes a bit deeper into the psychology of her adopted country.

Her desire for citizenship, she says, had other, more traditional underpinnings.

“I think that after the last election I thought I’d like to vote,” Ms. Ullman said this month at the production office in Santa Monica that she shares with her husband and collaborator, Allan McKeown, who is an executive producer of the series.

“I’ve been here a long time,” she added. “I’ve invested a lot of time in this country, and my children were born here, and I’ve had a really nice career here. It’s just something you want to do.”

And, of course, becoming a citizen provided an opportunity to gather an immense amount of new material.

“It’s a really interesting process,” she recalled. “Civics. Taking the test. Going for the interviews. I was interviewed by this lovely woman from Jamaica, who had become a citizen herself. And then I went downtown, with thousands of other people, in the convention center. And you all wave flags, and give your green card in, and they showed a film — Moon landings and waving wheat fields and monster trucks. President Bush came on and made a speech — silence — and it’s all scored.” And here she began to sing in a distinctly male, middle-American, country-and-western accent: “I’m proud to be an American because at least I know I’m free.”

Now, she added: “I finally feel a part of all that. It was something I wanted to do, and I’m glad I’ve done it. Because I feel political satire is fairly healthy in this country now. When I first moved here it was a little guarded and not as highly developed as in England. You couldn’t really make fun of the president when I first came here. There has always been ‘Saturday Night Live,’ which is a great thing to have, but now we have Jon Stewart and Colbert, and there’s much more of a sense of political satire.”

As part of that expanding American appetite for political satire Ms. Ullman has begun, for the first time in her long career, to impersonate real people, from the well known — Renée Zellweger and Andy Rooney, for example — to the less familiar but certainly topical types who inhabit the 24-hour news cycle, like the political pundit Arianna Huffington and the celebrity environmentalist Laurie David. The results, often hilarious and sometimes discomfiting, demonstrate that Ms. Ullman has lost none of her gifts for mimicry.

“She has an uncanny ability to, as an observer, cut to the absolute heart or core of a persona that interests her,” said Bruce Wagner, an author and occasional television writer who worked as a writer and producer of Ms. Ullman’s new series.

“Once she is in makeup and character, that is it for her,” he added. More than once, Mr. Wagner said, he would see someone he did not recognize out of the corner of his eye on the set of the show, causing him to have to look twice before he realized it was Ms. Ullman, continuing her usual practice of remaining in character as long as she was dressed and made up.

The format of the series loosely follows a day in the life of America, from dawn to midnight, with Ms. Ullman portraying an array of characters. Linda Alvarez, the nominally Hispanic news reader on WBFW-TV in Buffalo, where it is “5 a.m. and 5 below,” opens the morning news program. Proceeding through various cities and characters, the show ends, in a typical episode, as Ms. Huffington closes with her last dispatch of the day, wishing everyone “blogs and kisses” and cradling her laptop as she falls asleep.

In between, the television reporter Campbell Brown warns of the impending doom facing the nation; Padma Perkish, a Bollywood-aspirant pharmacist, dispenses musical advice on drug regimens and interactions; and Ms. David, flying in her vegetable-oil-fueled jet with the composting toilets, has her pilot dump fuel “over one of those red states.”

Ms. Ullman, who in the early 1990s sued Fox for a share of the merchandising profits from “The Simpsons,” which originated as a short feature on her Fox network series, long ago became financially successful. (The suit was settled with an undisclosed agreement.) Her latest move, to Showtime from HBO, resulted not out of animosity, both parties say, but from the evolution of both her and the networks.

HBO, more heavily reliant on serial drama and stand-up comedy, was no longer in the market for a sketch comedy show, executives there said. After Ms. Ullman changed talent agencies, she approached Showtime, which has been expanding its lineup of comedic dramas with series like “Weeds” and “Californication.”

Robert Greenblatt, president for entertainment at Showtime Networks, said he first met Ms. Ullman 20 years ago when he was “a very young drama series executive at Fox.”

“So when her agents came and asked if we would meet with her, naturally I said yes,” he recalled. At the meeting, during which she pitched the concept of the new series: “She did 10 or 12 different characters. She had already thought about who they were, and we could see the show unfolding in front of our eyes.”

Despite her sometimes acerbic take on her fellow Americans, Ms. Ullman said she truly means no harm. “I don’t see myself as a stand-up comic doing cynical, mean-spirited or disrespectful stuff,” she said. “I’m very aware that I don’t like to disrespect people too much. First of all I want to be funny, and I think people want to laugh. But there’s always something endearing in the characters. I just love to impersonate people, and I impersonate people because I find them fascinating.”