Oil prices are sliding on hopes of a last-minute US-Iran deal, but a rumor of a possible US nuclear strike on Iran threatens to upend that optimism just before the midterm elections.

• Crude oil fell sharply, with US prices dropping below $100 on reports that the US and Iran are negotiating again, and Iran reportedly has a proposal on the table for Trump to accept.
• A competing rumor claims Israel is pushing Trump toward a nuclear strike on an Iranian enrichment site, arguing conventional weapons can't reach it; a decision is said to be possible within about a week.
• Gas prices remain a kitchen-table issue for voters, some of whom hope ending the Iran conflict will bring prices down, even as the war risk itself threatens to send oil higher again.
• Midterm elections are tomorrow, with several Senate races in formerly safe Republican states now rated as toss-ups, a warning sign for the GOP.

Outlook: Oil could keep falling if a diplomatic deal with Iran materializes, but a US strike on Iran would likely send prices sharply higher and add major uncertainty right after the midterms.