Break out the pens and papers, “Veronica Mars” fans. If you want to see the teenaged sleuth on the big screen, you better start writing to Warner Bros.

“Mars” series creator Rob Thomas is a busy man these days. He’s got two shows, “Cupid” on ABC and “Party Down” on Starz, yet the project getting him the most attention is one that seems unlikely to be made: the film version of “Veronica Mars,” his cult-hit TV show.

“It’s not looking good,” Thomas said. “I wish I could report that it was. I think a lot of it hinges on the economy.”

Thomas said Joel Silver, who served as an executive producer on the TV series about a young private eye, called him many months ago in hopes of making the film.

“He called me six, seven months ago out of the blue and said, ‘Let’s do this,’” Thomas said. “But, at the time he called me I had four pilots launching. I had ‘Party Down,’ ‘Cupid,’ ‘Good Behavior’ and ‘90210,’ and it was like, ‘I don’t have another minute in my day, but as soon as I do, yeah, let’s do it.’”

Thomas finished work on the two shows that were picked up and said he immediately got to work on the pitch for the “Mars” film.

“I pitched Joel the most commercial version of a ‘Veronica Mars’ that I thought we could make at a price and Joel loved it, loved the pitch,” he said. “But, he couldn’t get the Warner Bros. people he needed excited about it excited enough.”

According to Thomas it all came down to a game of numbers.

“What they do is they actually run numbers on it,” he said. “They go out and test the marketing, the audience-awareness tests, and they actually did that and the numbers didn’t come back strongly enough for Warner Bros. to say, ‘Yeah, let’s do it.’”

While the pitch is not officially dead, it was not the immediate green light Thomas said he was hoping for.

When “Mars” was on the air, two seasons on the now-defunct UPN and one on the CW, fans constantly campaigned for the show to get a new season after the current one wrapped. Campaigns included flying a plane over UPN headquarters, sending thousands of candy bars, Mars Bars, to the CW headquarters and even holding DVD drives to get “Mars” DVDs in public libraries. But according to Thomas, there isn’t much left for the “Mars’” cult following to do.

“Multiply,” Thomas suggested and cautioned that while a plane over Warner Bros. headquarters might draw some attention, it won’t solve the current problem.

“I won’t say that [having a plane flown overhead] will mean nothing, but the numbers they get when they do audience-awareness testing, that means much more,” Thomas said. “Now I look at it and I think there are other young-people movies that don’t have any built-in audience when they get made. When they did the first ‘Fast and the Furious,’ no one had ever heard of that. Not that we’re doing ‘Fast and the Furious,’ but I mean I’m arguing into a void, it’s not like I’m sitting across from an executive pointing this out to him. I mean to them — I don’t even begrudge them this — it’s numbers on a page. It’s math. If Johnny Depp said that he wanted to guest star in the ‘Veronica Mars’ movie, suddenly there’d be a ‘Veronica Mars’ movie, but right now the math isn’t working for us.”

While Thomas didn’t complete a full script, he presented a pitch that was well received by all, but that’s not enough to cut it in today’s economy.

“Every day Kristen Bell [star of the series] gets a little older works to our disadvantage,” he said. “Part of the magic of the show is that she’s a young, female private eye and so it’s tough because Kristen and I both had a window right now, and now that window I think is evaporating and I think that’s largely the result of the economy.”

While the movie may be on the back burner for “Mars,” could the show go the route of other cult-hit TV shows and venture into different mediums, like comic books and Webisodes? Thomas said it’s unlikely. According to Thomas, Warner Bros. owns the rights to “Mars,” and they’re not in the market for Web films. But, Warner Bros. owns comic book company DC Comics, a venture Thomas had talked about immediately after the show’s demise.

“If the writers’ strike had lasted another couple of months, I might’ve gotten to the comic book series, but given the strike, given the short ‘Cupid’ season, I currently need to make TV money,” he said. “I’m not currently in the position to make comic book money. Honestly, I think Warner Bros. would probably finance a direct-to-DVD movie, but I doubt either Kristen or I would want to do it. It’s a slippery slope when you become the guy who does direct-to-video projects. I wouldn’t want to burn the chance to do ‘Veronica Mars’ right.”