Late in his blitz to salvage Republicans' midterm fortunes, United States Vice-President JD Vance has shifted strategy. He talked less about President Donald Trump and more about the issues that define his own political identity.

Vance argued the case for Republicans, who lost control of Congress, almost exclusively through the lens of his policy portfolio, according to a Reuters review of half a dozen speeches since the Republican convention in September.

He bypassed Trump's signature policies, including the Iran war and deportations, as polls showed the president's sagging popularity dragging down Republican office-seekers.

The change was deliberate, according to two people familiar with the strategy.