By Elisabeth Smith

SACRAMENTO (CBS13) — The Sacramento County Board of Supervisors is being asked to investigate a supervisor over his Facebook post about supporters of President Trump.

In a letter to the Sacramento County Board of Supervisors Thursday, the Sacramento County Deputy Sheriff’s Association (SCDSA) called for a formal investigation into the post from Jan. 3.

READ MORE: Man Killed In Sacramento Freeway Shooting Was Retired Correctional Officer Lufino Reyes Mejorado

In the scathing Facebook post, Phil Serna wrote “If you are a supporter of Donald Trump, you’re dead to me. You don’t matter. You are irrelevant. You are a traitor. Hope that’s clear.”

On Wednesday, the union calling the post a “shocking display of hatred,” and said, “a bias that alienates and scorns a significant percentage of the constituency living in his district should not be tolerated.”

The SCDSA has called for the board to remove Serna if he does not step down.

In the letter Thursday, the union’s attorney claims Serna’s Facebook post violated county discrimination policies which prohibit discriminating against a person because of their “political affiliation or belief.”

They claim Serna used social media to “distribute and display slurs and derogatory comments about Trump supporters.”

READ MORE: Experts Discuss Omicron COVID-19 Variant Findings In Sacramento Wastewater

Because he is an elected official, the county will be required to use an outside investigator in an investigation into his conduct.

Serna issued a statement Thursday, calling the complaint “entirely meritless.”

“The complaint filed against me for exercising my First Amendment right to free speech on my personal Facebook page is entirely meritless, and I expect any investigation will bear that out. Furthermore, it is puzzling and confounding that the complainant – Kevin Mickelson, President of the DSA and proud, unabashed Donald Trump supporter, is so focused on my personal Facebook page when there are so many other pressing matters affecting his members. If he and his association are so intent on advocating someone be removed from office, they might want to focus on Donald Trump himself, just as The United States Congress is doing,” Serna said in the statement.

CBS13 has reached out to the county for a comment on the matter but has not heard back.

Fellow Sacramento County Supervisor Sue Frost responded to those online comments Tuesday. In a statement, Frost said, “No elected official should disdain their own residents.  I think all people are relevant, no matter what political candidate they happen to support.”

MORE NEWS: Renowned Roseville Taqueria Nixtaco Hit by Crook Caught On Surveillance Camera

More from CBS Sacramento: