Alarmed at recent moves by leftist groups to silence opposition voices, conservative talkers across the country are creating an audio chain letter of support.

Based on their dislike of his topic choices, a well-funded, partisan effort by Media Matters For America is pressuring Sean Hannity’s advertisers to drop the show.

Writing at Talkers, a radio industry trade publication, longtime host Phil Valentine (above image) says “corporations tend to react when cowardly sponsors pull their money at the first sign of trouble. Why these sponsors signed on to an opinion show in the first place is puzzling. But if there’s not pressure pushing back from the other side, those who wish to force their agenda through intimidation will always win.”

“Too many of us in broadcasting stand idly by while our colleagues are destroyed by people who claim to love diversity except when it comes to diversity of thought. We stand on the sidelines while colleges cancel speeches by speakers who a violent, vocal minority don’t want to hear. We climb back into the cozy confines of what’s acceptable speech instead of standing on the battlefield of free speech, shoulder-to-shoulder with our brethren who endure these withering attacks,” Valentine added.

Mark Levin, a nationally syndicated conservative host and attorney, is speaking out as well, offering legal advice.

Via Facebook, he told followers that the Fox News Channel host should consider filing suit: