PUBLIC sector workers, angry over pensions, are threatening to disrupt next month's local elections.
The warning came today after a 24-hour walkout was declared a huge success.
More than a million workers across the country joined the industrial action.
In Huddersfield, schools, libraries, refuse collections and housing offices were among services hit.
Unions are now threatening to hit council elections with a 48-hour stoppage on May 3 and 4.
It will follow three days of action earmarked for April 25, 26 and 27 in different parts of the country.
Paul Holmes, Kirklees branch secretary of Unison, said: "Nothing has been decided officially, but I would say it is almost nailed on that there will be a strike on election day.
"There's been a lot of pressure from our members to do it on that day.
"They feel so strongly on the issue and are in this for the long haul."
A strike over election day would make it impossible for polling to take place, said Mr Holmes.
"Of the 300 clerks needed, 90% would be our members," he said.
Workers from 11 unions joined yesterday's one-day strike.
They are angry at Government plans to scrap a deal which allows them to retire at 60.
Unions said it was right that a deal was struck last year to protect the pensions of civil servants, teachers, health workers and other public sector employees.
Mr Holmes said: "If it is good enough for them it is good enough for others."
Just two of the 3,000 Unison members based inside Huddersfield ring road are reported to have worked yesterday.
The town's Queensgate market remained shuttered.