A local union representing dozens of behind-the-scenes workers at WBZ-TV has shut down a face-to face debate between Mayor Martin J. Walsh and City Councilor Tito Jackson.

The International Brotherhood of Electrical Workers, Local 1228, sent a letter to both men this week urging them to boycott Tuesday’s proposed debate until the television station and its parent company, CBS Boston, agree to higher wages for longtime employees.

Both men agreed to support the union’s wishes.

“I [will] not cross the picket line,’’ Walsh told the Globe.

“I will not be participating,’’ Jackson also said.

With both men siding with the union, WBZ said it had no choice but to cancel the debate.

“Without candidate participation we cannot host a debate on Tuesday night, ‘’ said a statement from WBZ management.

Jackson said he is seeking a debate with a different news organization.

The Walsh campaign had announced last week that the mayor had accepted an invitation to debate Jackson on the Dan Rae show Tuesday, on WBZ News Radio. The mayor also accepted an invitation from WGBH for Oct. 24.

Jackson had not committed to either of those dates.

Jackson criticized the mayor for “unilaterally’’ scheduling the two debates, including one at a location “where the union is working without a contract’’ since last year. He urged both sides to agree on a contract. “I believe that all workers should be paid fairly,’’ he said.

Local 1228 wrote that it had been in negotiations with WBZ-TV and CBS Boston since December. As the debate date approached, union officials first asked Jackson — and the councilor agreed — to not appear on WBZ. The union represents technicians, photographers, engineers, and master control operators, said Fletcher Fischer, Local 1228’s business manager and financial secretary, who sent the letter.

“For years, management has been engaged in suppressing wages to the point where average wages are drastically lower than their counterparts in the Boston television market,’’ Fischer’s letter said.

“Veteran workers with decades of service to WBZ-TV are working side by side with newer workers who make hundreds of dollars a week more for the same work.’’

The letter urges all political candidates and officeholders not to appear on any CBS Boston entity — WBZ-TV, Channel 4; WBZ News Radio (1030 AM); the Sports Hub (98.5 FM); or mytv38 — or purchase or display ads until a new contract is signed.

“We are targeting everybody,’’ Fischer said.

In a statement, WBZ-TV said it “has been actively involved in negotiations and made what we believe to be a fair offer that union membership has rejected. We are committed to continuing our conversations with the union.’’

Irons can be reached at meghan.irons@globe.com.