Republican Congressman Thomas Massie is in a tight, brutally expensive primary that has become a test of whether anyone can stay independent from Trump.

• At $35 million plus, it's the most expensive US House primary ever, funded largely by out-of-state billionaires like Miriam Adelson and Paul Singer.
• The three priciest House primaries in history all targeted incumbents who broke with the pro-Israel lobby, and this fits the pattern.
• Massie also angered Trump by pushing to release the Epstein files, so Trump is attacking him nonstop online.
• His opponent, Ed Gallrein, leans on a vague "classified" Seal Team Six background and Trump's backing rather than specifics.
• Polls show a dead heat with a big age split: younger voters back Massie, older primary voters back Gallrein, and Kentucky's closed primary hurts Massie.

Outlook: The race is a coin flip, but momentum has shifted toward the Trump-backed challenger, and even Massie admits he could lose.