BRUSSELS — The largest group in the European Parliament is threatening to reject a key part of the European Commission’s multiyear budget proposal in November. In a major confrontation, the European People’s Party (EPP) — from which Commission President Ursula von der Leyen and most of her commissioners hail — renewed a threat to refuse to support the proposal if it doesn’t get major concessions on money for farmers and Europe's regions. “If the Commission ignores our demands, our members see a