Audi has said it will spend $4bn (£3bn) to build its first factory in the US, as its parent company, Volkswagen, struggles with the impact of steep tariffs imposed by Donald Trump.

The German brand’s chief executive, Gernot Döllner, joined Trump on stage at a campaign rally on Saturday night to announce the factory in Macon, Georgia , in an unusual move by a big European brand just days before the US midterm elections.

The Republican party under Trump is trying to retain control of both houses of Congress, but it is polling poorly as it struggles with higher fuel prices caused by Trump’s war on Iran , as well as his trade war against some of the US’s biggest trading partners.

Trump has long tried to convince voters that his tariffs are helping to increase the number of manufacturing jobs in the US, and has seized on any new factory investments.…