Potential strike action on the main rail services into Watford, Bushey, and Kings Langley moved a closer as talks between London Midland and a union hit a stalemate.
Bosses at the RMT rail union said the rail operator’s plans to axe 150 jobs was a "gun to the head" of its staff and threatened to recommend its members strike.
The union said industrial action could be averted if London Midland bosses engaged in "meaningful negotiations" over the planned cuts.
RMT Acting General Secretary Mick Cash said: "The cynical attempt to claim that the 150 jobs threatened are not important is a kick in the teeth for staff who make London Midland tick - the plans have generated a wave of anger across all grades since they were announced in March and we are rapidly losing patience as the company drags its heels in the talks.
"We have further talks this week but the company should be under no illusions. If they don’t lift the gun from our members’ heads, and get proper and meaningful negotiations back on track, we will take a report to the Executive recommending a ballot for action."
The dispute broke out in March after London Midland announced it planned to cut scores of jobs as the company was under pressure from rising costs.
Patrick Verwer, managing director of London Midland, said: "The service to our passengers will not be affected by the changes. We have made good progress over the last year. Our train service is much improved and higher customer satisfaction scores tell us passengers can see the difference."