President Donald Trump promised $8 billion in federal aid for farmers Monday, pitching the plan at a campaign rally in Park City, Kansas, for Republican Sen. Roger Marshall, who faces a tough race this November. The proposed payments are intended to help farmers cope with high diesel prices. But the details are not yet settled: farmers may wait several weeks to learn what they could receive, and payments would not arrive until late November or early December at the earliest, according to people familiar with the plans. The proposal may also face a fight in Congress. That timetable could blunt the political impact. The announcement came about two weeks before Election Day, meaning voters may head to the polls before any money reaches producers—and before they know how much they might get. The administration is trying to ease discontent in agricultural states, where farmers and ranchers have been squeezed by high fuel costs amid the Iran war and angered by Trump’s tariffs and increased imports of foreign beef. Rural voters are an important constituency for Republicans, and the new aid pledge puts taxpayers on the hook for a costly intervention whose final terms and prospects in Congress remain uncertain.