The union representing Deutsche Bahn AG railway drivers and related staff began voting on Monday to decide whether to go on a nationwide strike amid a push for a 31 percent wage increase.

The GDL union needs a 75 percent backing of its 32,000 members. The results are expected by August 6 and a strike could follow soon thereafter.

Last Thursday, union and Deutsche Bahn officials ended negotiations without a result after previous attempts. The union says the current driver pay of 1,500 euros ($2,075) per month is not enough.

The labor action could be the first unlimited strike in 15 years and would occur in the middle of the summer travel season when many Germans are vacationing.

After the talks broke off, Deutsche Bahn’s management board member, Margret Suckale, criticized the trade union for showing “no readiness for compromise.”

Deutsche Bahn is a state owned firm. According to reports, the German government will offer up to 30 percent to the public next year, which could raise between 5 billion euros and 6 billion euros ($6.9 billion and $8.3 billion).