BRUSSELS (AP) — Hundreds of tractors driven by angry farmers protesting a plan to cut nitrate levels were headed to Brussels on Friday, with major traffic disruption expected across Belgium’s capital city.

The BB farmers union and several others were combining efforts and were expecting more than 2,000 tractors. Police warned that disruptions could last until the end of the day and recommended people use public transportation instead of personal cars.

The Flemish regional government is struggling to find a deal to cut nitrate pollution over farmers’ objections that it would put many out of business.

Farmers also claim that their trade has to make much deeper cuts than industry and want to see a more equitable spread. Negotiations have lingered for weeks and weakened the regional government of northern Belgium to breaking point.

The debate over agricultural pollution is increasingly turning into a political issue in many of the EU’s farming nations. It is to be a focal point of Dutch elections in two weeks’ time and is also affecting Belgium, another EU nation where intensive farming has put environmentalists against the agricultural lobby.