President Donald Trump has talked up his controversial tariffs, saying they will revive the US steel industry, as he campaigned in Pennsylvania steel country for a Republican congressional candidate Rick Saccone in a tight race.

A day after getting news that the US economy produced 313,000 jobs last month, Mr Trump says his policies are paying off.

Mr Trump vowed to fight any retaliatory trade measures by, for example, slapping taxes on imported European cars.

He told the big crowd that coal is making a comeback.

Mr Saccone is trying to win an election on Tuesday in Pennsylvania's 18th District to replace Republican Tim Murphy, who resigned in the midst of a sex scandal.

He is competing against Democrat Conor Lamb and polls show a close race.

The Republicans won Pennsylvania in the presidential election.

Trump has also announced the slogan for his 2020 presidential re-election campaign - 'Keep America Great!'