Conservative radio shock jock Rush Limbaugh may be considering ending his partnership with Cumulus Media later this year, potentially signifying a momentous shift in the talk radio landscape.

Sagging ad revenues and a disagreement between Limbaugh and Cumulus CEO Lew Dickey are the cause of the potential move, a source close to Limbaugh’s show told Politico on Sunday.

If Limbaugh decides to sever ties, 40 Cumulus-owned radio outlets will lose access to "The Rush Limbaugh Program," considered to be the most popular talk radio program in the nation, Politico reports. Additionally, the show may be featured on competing regional radio stations in New York, Washington, Chicago, Dallas and other markets.

According to the source, Limbaugh and Dickey have been feuding over the Cumulus executive's claims that WABC’s drop in ad revenue is a direct result of Limbaugh’s inflammatory statements about Sandra Fluke, Politico reports. In February 2012, Limbaugh called Fluke “a slut” after she petitioned congress to enact mandatory insurance coverage for birth control. The comments caused several major advertisers to boycott Limbaugh’s program.

While Dickey maintains the Fluke incident caused a “residual hangover” for the station’s ad revenue, sources close to Limbaugh remain unconvinced.

“Lew needs someone to blame, [so] he’s pointing fingers instead of fixing his own sales problem,” a source close to Limbaugh reportedly told the New York Daily News.

A source added that the boycott was ineffectual, claiming that revenue was “very minimally impacted in the short term,” the New York Daily News reports.

While Dickey claimed in August that Cumulus’ top three stations had lost $5.5 million, Limbaugh remains the highest-rated talk radio host in the nation, Politico reports. Limbaugh’s contract with Cumulus runs through the end of 2013.

So far, Cumulus Media declined to comment on Politico’s report. "Cumulus owns the premier talk radio distribution platform in the United States and doesn't comment on negotiations with talent under contract," spokesman Davidson Goldin told Politico.

As Cumulus’ Tuesday earnings call looms, any additional comments by Dickey regarding the Fluke incident’s influence on ad revenue may impact Limbaugh’s decision.

“It’s a very serious discussion, because Dickey keeps blaming Rush for his own revenue problems," the source close to Limbaugh’s show told Politico. "Dickey’s talk stations underperform talk stations owned by other operators in generating revenue by a substantial margin. It’s not a single show issue ... it’s a failure of the entire station. And trying to blame Rush for that is not much of a business partnership."