TAMPA — Bubba the Love Sponge Clem fired off a few texts to one of his radio show's listeners one day in September, just like he had the last several weeks.

The listener had a device that the ratings giant Nielsen uses to measure how popular radio programs are, and Clem had been talking to him since late July, offering cash if he followed instructions of what to listen to and when.

This time, on Sept. 5, Clem's tone was especially urgent, according to documents filed in federal court by Nielsen late last month. Earlier in the week, another listener in Nielsen's survey had had his device deactivated. Clem was worried his ratings would fall, so he asked the man to be especially careful to avoid getting caught.

"I need u more than ever," Clem texted, according to the court filing. "U are the last one I got in this game."

It was too late. The listener had turned him in to Nielsen the month before, setting in motion a scandal that threatens to take one of Tampa's most famous shock jocks off the air in a case that industry experts say has little precedent.

Nielsen filed suit against Clem in October, saying he tried to change that listener's behavior and claiming $1 million in damages. Clem, born as Todd Clem but better known as Bubba the Love Sponge, apologized for trying to influence him.

But the latest allegations suggest that it wasn't a one-off mistake. Nielsen now says Clem asked five people — four in the Tampa Bay area and one in South Carolina — to help him boost his numbers as early as last year. In the initial case, he's accused of offering weekly cash payments and performance bonuses.

Clem hasn't yet filed a response to Nielsen's allegations, and on his show Tuesday, he said he couldn't address them publicly.

His attorney, Todd Foster, declined to comment on the accusations, but said he will move later this month to have U.S. District Judge James Whittemore dismiss the lawsuit, arguing that the case doesn't belong in federal court.

"There are three sides to every story — their side, my side and the truth. And two sides of this story hasn't been told yet," Clem said Tuesday.

The allegations have raised the possibility that Clem's show could be pulled from the air by Naples-based Beasley Broadcast Group, which airs the program on stations including Tampa's WBRN-FM 98.7 — a prospect Clem acknowledged this week.

"It's up in the air. It is. I'm gonna be honest with you," Clem said on his Tuesday show.

Soni Dimond, a spokeswoman for Beasley, said the company had no comment on the case.

Beasley Broadcast president Bruce Beasley said in a statement last month that the company had "instituted remedial action" like additional training for Clem and was working with Nielsen because "we were also victimized by Mr. Clem's actions." The company took a hit when Nielsen pulled ratings for WBRN from its reports in September and October, a potentially costly and embarrassing decision.

Nielsen's latest allegations suggest Clem had been talking to survey participants for months, which the company says violates its rules.

In one case, a man in Charleston, S.C., tweeted at the radio host to say he'd been picked for the survey; Clem allegedly asked to talk on the phone and later thanked him for "hooking me up," according to the lawsuit.

In others, Nielsen says it noticed sudden changes in its panelists' listening habits. It alleges, for example, that one man in the Tampa area listened to WBRN for 189 hours in a month after logging just over an hour in the previous three. He later told Nielsen that he worked at night and usually slept while Clem's show was on-air.

Clem has had plenty of high-profile tangles with scandal and legal drama throughout his career.

In 2001, he was charged with animal cruelty after he presided over the castration and slaughter of a pig on the air. (He was later acquitted.)

In 2004, he lost his job at Clear Channel after racking up $755,000 in fines from the Federal Communications Commission for segments regulators deemed indecent.

In 2006, he recorded a video of Hulk Hogan having sex with Clem's ex-wife, a tape that was later leaked to Gawker, an online media company. (Hogan and Clem settled a lawsuit out of court.)

And this year, the lawyers that defended him in a high-profile defamation suit could be barred from practicing law. The allegation against them: They set up the attorney representing a rival DJ and had him arrested for drunken driving.

Clem has survived those bumps in his career. He has managed to pull down seven-figure salaries, and after being pushed from traditional radio, he went national, inking a deal with Howard Stern to do a show on Sirius satellite radio before returning to the Tampa market.

But industry followers say the additional allegations of ratings tampering deepen his latest scandal — one that once again threatens his future on the air.

"Cheating is cheating," New York-based radio consultant Valerie Geller said in an email. "While multiple incidents is worse than one, one is bad. It's ballot stuffing, and if you are caught, there are severe consequences."

It's rare for a host to be accused of cheating, much less to be sued for it, said Michael Harrison, publisher of the trade publication Talkers magazine.

It has become even less common as Nielsen has moved away from asking its survey subjects to keep a log of their listening habits. In many markets, including Tampa Bay, the company has instead distributed devices that register radio signals. They even record movement and location to make it harder to cheat.

The allegations are a devastating blow to Clem's career, Harrison said, because so much is tied up in radio ratings: A boost of just one or two points could be worth hundreds of thousands of dollars in ad sales.

And that could damage Clem's prospects even if he's allowed to stay on the air as the allegations cast doubt on his numbers.

"I don't know if it's the end of his career, but I do know that it's certainly a major setback," Harrison said. "It's injured his prestige. It has made questionable his numbers. … This thing has gotten so much attention that it will stick for a long time."

Reach Thad Moore at tmoore@tampabay.com. Follow @thadmoore.