Just as Montreal welcomes the world’s top cyclists, more than 6,000 blue-collar workers who help keep the city running could walk off the job.

The workers gathered at Champ-de-Mars begins around noon Saturday, leaving the municipal administration 36 hours to avert a walkout, according to the Montreal Blue-Collar Workers Union, CUPE 301, in a statement.

Blue powder was sprayed by supporters during the demonstration.