Trump's 39-year-old VP pick is expected to appeal to younger right-wing voters, especially in swing states.
The Republican National Convention is continuing in Wisconsin.
Ohio Senator JD Vance has been announced as Trump's running mate, with Trump also making an appearance at the convention.
US correspondent Richard Arnold told Mike Hosking that despite not liking Trump in 2016, Vance has since embraced the MAGA campaign in every way.
He says policy wise, Vance believes Latin American immigration is killing jobs for people in Ohio and letting Democratic voters pour in.
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