Aaron Sorkin, creator of “The West Wing,” is excited about the upcoming fourth season, mainly because “it’s no longer last season.”

The third-season “West Wing” was thrown for a loop by Sept. 11 and never quite recovered.

Actors Rob Lowe, left, Richard Schiff, behind Lowe, Bradley Whitford, gesturing, and Allison Janney appear in a scene from NBC's The

“Last season was a continual search for what I wasn’t doing that makes the show work,” Sorkin told a teleconference this week. “We just all felt all year long like we were doing something wrong, and we just couldn’t put our finger on it.”

There were things people needed from entertainment after the terrorist attack, Sorkin says, including comedy and escape. “Fictional heroes weren’t one of them.

“Fictional heroes, I think, were a bit in bad taste. Because our hearts were so completely with the real ones,” he says.

For a show that depends on nuance, Sept. 11 didn’t fit, Sorkin says. “It was one of those rare moments where things are black and white, when there’s a moral absolute.”

He yanked last September’s season opener and inserted a talky replacement that played more like a public-service announcement.

“I didn’t think that it was right that it just be a regular episode of ‘The West Wing,’ that people be tearing around the corridors and flirting with each other and being glib,” Sorkin says. “Some sort of respect had to paid to the event that just happened.”

But the special episode didn’t go over very well.

“I don’t think that it was a good episode of ‘The West Wing’ either,” he says. “I’m not even sure it was good television. But what I do know for sure is that it was well-intended.”

Only one president

After which, the series couldn’t quite find its footing.

“There’s a tricky problem when you’re writing ‘The West Wing’ that I don’t think you have when you’re writing a hospital show or a cop show or a lawyer show. And it’s the problem of suspension of disbelief,” says Sorkin, who previously brought the sitcom “Sports Night” to the small screen and wrote feature films, “The American President” and “A Few Good Men.”

“There’s more than one emergency room in Chicago, so we have no problem believing these ‘ER’ people are there. And there’s more than one police precinct in New York, and there’s more than one law firm in Boston, and so on and so on.” But, he adds, “There’s only one president. And there’s only one White House. And that’s how it gets trickier.”

President Josiah Bartlet and his staff live in an alternate universe, contemporary but apart from the real world. “There are certain sorts of vague gauges and dials that we follow on the show in terms of mentioning anything contemporary, which we seldom do,” Sorkin says.

So terrorism as a daily concern is played down in the show, though it can’t help but seep in. “This new global threat, terrorism, is part of the water supply now,” Sorkin says. “Even in episodes that don’t directly deal with it.”

The new atmosphere led to a plot turn last season that might otherwise have seemed out of character for Bartlet: He approves the covert assassination of a foreign defense minister.

“How this devout Catholic and lover of the law is able to assassinate someone,” Sorkin said. “It’s very interesting to me.”

Sorkin says he couldn’t help but be influenced by 9-11.

“My Etch-a-Sketch has gotten as shaken up by Sept. 11 as everyone else’s,” Sorkin says. “Will that find a way into the writing? Of course.”

Moving forward

But already “The West Wing” is taking a lighter tone. In the two-hour season premiere Sept. 25, titled “Twenty Hours in America,” part of the plot involves three White House staffers Toby Ziegler (Richard Schiff), Josh Lyman (Brad Whitford) and Donna Moss (Janel Moloney) who are left behind when the motorcade leaves a campaign stop.

With two new recurring characters this year Lily Tomlin at Mrs. Landingham’s old desk as the president’s secretary, and Mary Louise Parker in a role as Josh’s love interest and another undisclosed romance to bloom, Sorkin feels more confident about the show’s direction.

“When I came back to begin writing the show,” he says, “I suddenly felt comfortable in my chair again. The show felt good and fun and it felt right. I think that the cast and crew felt that way, too.”