For rest and relaxation, some U.S. senators make a run for the Oval Office. Some raise slush funds for their campaign war chests. Barbara Boxer likes to write fiction. And now California’s junior senator makes her debut as a novelist with “A Time to Run.”

The novel’s lead character happens to be a diminutive female senator from California, an unabashed outspoken liberal from the Bay Area.

But Boxer insists her novel is not autobiographical.

“I’m 15 years older than her,” says Boxer of her protagonist Ellen Fischer. “I never sat down to write about me.”

Despite superficial similarities, art in this case did not exactly imitate life. Rather than make Ellen a Jewish child of the Eisenhower-era like herself, Boxer made her a baby boomer during the Watergate era. Ellen’s husband, Josh, is a committed Jewish liberal activist, the son of Holocaust survivors and a bit of a tortured soul. When Josh dies, Ellen takes over his campaign for the senate and wins.

This doesn’t give away any plot twists. The novel opens with Ellen ensconced in the Senate pondering — of all things — the nomination to the Supreme Court of a conservative woman lawyer-friend of a Republican president.

Completing the triangle is journalist Greg Hunter, Josh’s best friend, Ellen’s one-time flame and a double-crosser who goes over to the dark side. He becomes a clandestine Republican operative out to sink both Josh and Ellen.

But even with Greg Hunter and his creepy mentor Republican Sen. Carl Satcher, Boxer tried to make her characters three-dimensional. She even has Satcher make a case for the conservative view of life and politics.

“I wanted to show these people as human beings,” she says, “and all the stresses and strains. The politicians I get along with best are the ones that believe they’re doing the right thing, whether liberal or conservative.”

Boxer’s emotionally complex tale owes more to Jane Austen than John le Carré. But she does offer a lingering glimpse of the political mind and how personality and passion shape political ends.

The novel also has plenty of sex (though tame by Danielle Steel standards), something not normally associated with the hallowed halls of the Senate. Says Boxer: “If you write about real life, you write about real life.”

The novel is also a love letter to the Bay Area, mostly set in the East Bay, not Boxer’s home turf of Marin County.

As busy as she is, it’s a wonder Boxer ever had time to sit down and write at all. But that’s what transcontinental flights are for. While traveling back and forth between coasts, Boxer methodically sketched out the novel.

And it only took her seven years.

“I worked on the book alone for four or five years.,” recalls Boxer. “Then I spoke to my agent and said, ‘I’ve taken it far, but I feel it could be better.”

That’s when novelist Mary-Rose Hayes came into the picture. Hayes collaborated with Boxer to shore up plot points and character development. “We were a perfect team,” says Boxer. “We hit it off right away and it really worked.”

Boxer swears she never once caught herself daydreaming about her book while sitting in some boring Senate committee hearing.

Says Boxer, “You can’t go off on a tangent. You get in another mind set and put everything else out.”

It’s too soon for Boxer to speculate who might play Ellen in the movie version of “A Time to Run.” And it’s certainly too soon to say if she has another novel in her.

But Boxer says among the lessons she’s learned in politics, some apply to her career as a budding Hemingway.

“Go with the flow,” she says, “one step at a time and never say never.”

“A Time to Run” by Barbara Boxer ($24.95, Chronicle Books, 320 pages).