President Donald Trump's political groups have spent more than one-quarter of a billion dollars to bolster Republicans in the final stretch of this year's midterm elections, an unprecedented amount for a sitting president that underscores the stakes on Nov. 3.

"I endorse American candidates, and that's where I'm focused on the midterms," Vice President JD Vance said.

The shifting money in the final weeks of midterm campaigns points to a defensive posture by Republicans and new aggression from Democrats, who aim to capitalize on President Donald Trump's weak approval ratings.