The reforms are aimed at reversing falling sales and reducing "wine lakes" costing hundreds of millions of euros to get rid of.
The European Commission says the bloated wine sector must cut overproduction or risk further decline against cheaper wines from New World and other overseas producers.
Its plan suggests pulling up unprofitable vineyards, ending subsidies for massive and costly distillation of unsold wine into industrial products and harmonizing labeling to make it more consumer-friendly.
It also foresees a ban on adding sugar to wine produced in regions with a cooler climate - a plan the majority of countries in the 27-member bloc oppose. Vintners in areas with a lack of sun, including Germany, Austria, Luxembourg and the Czech Republic use extra sugar to produce higher-quality wines.
"The blanket ban on sugar is a problem. The European Commission will have to modify its proposal," said Czech Agriculture Minister Petr Gandalovic.
The Commission and the Portuguese EU presidency were to discuss the draft reform separately with each of the 27 EU member nations, sounding out conditions under which they would go along with the proposals, officials said. The debate was to continue into Tuesday.
An agreement on how far the reform will go could be reached by the end of the year, diplomats said.