Donald Trump returned to the campaign trail on Tuesday night with a familiar refrain, criticising Mexico for failing to stop the flow of illegal immigrants to the US and promising to make Mexico pay for his proposed border wall.

And the result was the same: Enthusiastic cheers from supporters in Nashville, Tennessee, followed by a swift promise from the Mexican president that no such thing would ever happen.

Mr Trump took his message out on the road as part of efforts to shore up Republican votes during what could be tricky mid-term elections in November.

Democrats hope an unpopular president could help them wrest back control of the Senate and the House of Representatives.