Five National Union of Journalists chapels have voted to take industrial action over Trinity Mirror's plans to introduce individual online traffic targets for journalists.
The union said the "individual digital audience goals" are currently being trialled at the Manchester Evening News and are set to be rolled out across the group next month.
It said titles affected by the strike vote inclide the Daily Post in Wales, Liverpool Echo, Coventry Telegraph, Birmingham Post and Mail and the Newcastle Chronicle. A strike vote result from the Manchester Evening News is expected next week.
The NUJ said members were concerned the targets would impact on cooperation and collaboration in newsrooms and undermine investigative journalism.
Chris Morley, NUJ coordinating officer for Trinity Mirror, said: “It is unprecedented for six chapels to be balloting over the same issue at the same time at Trinity Mirror.
"With five of the results in, the discontent over individual goals or targets is clear to see and has been translated into strong votes for potential industrial action.
"This is a wake-up call to the company to listen to our members’ legitimate concerns and work with us in a constructive way to achieve the company’s goal of a bigger digital audience.
"The more members see of the proposals for individual goals/targets, the more they don’t like them.
"We are continuing to talk to the company about their need to boost the digital audience, but I hope senior managers now realise that they need to win both hearts and minds and that the proposals, as they stand, do neither."
General secretary Michelle Stanistreet said: "Our members could not make their concern and fears about the individual digital targets more clear.
"They understand the need to measure the digital output and the need to increase the digital audience, but the solution is to encourage well-resourced and well-managed newsrooms where everyone can play their part, not put the staff under the pressure of having to hit individual targets.
"Let's hope the result of these ballots will concentrate the minds of management to have constructive talks with the NUJ."
Trinity Mirror regional editorial director Neil Benson has previously defended the online audience targets and said they are not about promoting 'clickbait' style journalism.
He said: "We won’t just be measuring page views and unique users – we’ll be looking at engagement as well.
"That’s equally important, building up an engaged local audience who come back and use us.
"That’s the opposite of what you were doing if you were just aiming for clickbait. What we want is loyal local readers who come back to us all the time."