Kentucky Republican Thomas Massie is in a tight primary fight as Israel-aligned donors pour millions into unseating him, bad news for anti-war conservatives and a warning sign about foreign-funded influence in US primaries.

• Massie angered Trump by pushing to release the Epstein files and voting against spending on Israel's wars.
• Miriam Adelson, MAGA Kentucky, the Republican Jewish Coalition, and AIPAC's super PAC have poured over $13 million into backing challenger Ed Gallrein.
• Total spending tops $25 million, making this the most expensive US House primary ever.
• An ex-girlfriend's last-minute hush-money and abuse claims hit the press days before the vote, which Massie's camp calls a dirty trick.
• One recent poll shows Gallrein leading Massie 48% to 43%, though the pollster's methods are questioned.

Outlook: The race is within the margin of error and will likely come down to turnout in next week's primary.