AFP, Pittsburgh

Kamala Harris blasted Donald Trump as the “biggest loser” on the economy and a friend of billionaires Wednesday as the election rivals laid out competing plans on the top issue for many US voters.

In a speech on the economy and then again in her first major solo interview, the Democrat warned that Trump’s plans to bring back huge tariffs on foreign imports would hurt middle class Americans in their wallets.

Republican Trump for his part doubled down on his protectionist vision -- but spent as much time on threatening to blow Iran to “smithereens” after US intelligence warned of threats from Tehran against his life.

The vice president and the former president are neck-and-neck in polls and are both reaching out to undecided voters on key issues like the economy with less than six weeks until election day.