Member states will vote on Friday on an almost complete ban on the use of neonicotinoid insecticides across the EU.
Scientific studies have linked their use to the decline of honeybees, wild bees and other pollinators.
The move would represent a major extension of existing restrictions, in place since 2013.
Manufacturers and some farming groups are opposed, saying the science remains uncertain.
Neonicotinoids are the most widely used class of insecticides in the world, but concerns about their impact on bees have been reinforced by multiple research efforts, including so-called "real world" trial results published last year.
Change of heart
Back in 2013 the European Union opted for a partial ban on the use of the three chemicals in this class: Imidacloprid, clothianidin and thiamethoxam.
The restrictions applied to crops including maize, wheat, barley, oats and oil seed rape. The new Commission proposal would go much further, meaning that almost all outdoor uses of the chemicals would be banned.
The action has been driven by a recent report from the European Food Safety Authority (Efsa), which found that neonicotinoids posed a threat to many species of bees, no matter where or how they are used in the outdoor environment.
Another key element that has pushed the Commission to hold a vote has been the UK's change of heart on the use of these insecticides. Environment Secretary Michael Gove announced last November that the UK would now support further restrictions.
"I think it has helped the dynamic," Franziska Achterberg from Greenpeace told BBC News.
"It has helped sway Ireland definitely, and then lately, the Germans, the Austrians and the Dutch. I think the fact the UK had come around was a good signal for them as well, that they could not stay behind."
During the partial ban, some countries including the UK were given permission to use neonicotinoids for short periods. However, the EU Commission is now signalling that it is seemingly intent on pushing the proposal through as it stands.