Donald Trump warned Tuesday of “very bad things” if Republicans lose the US midterm elections, as the US president kicked off a travel blitz under the shadow of unrest in Minneapolis and voter worries about the economy.

At a rally in Iowa -- one of the first stops for primary campaigns in US presidential elections -- Trump said his party must win both the Senate and the House in November despite his own poor approval ratings.

“I’m here because I love Iowa, but I’m here because we’re starting the campaign to win the midterms. Got to win the midterms,” second-term president Trump said in his speech.

“If we lose the midterms, you’ll lose so many of the things that we’re talking about, so many of the assets that we’re talking about, so many of the tax cuts that we’re talking about -- and it would lead to very bad things.”

But Trump’s economy-focused speech was largely overshadowed by events in the neighboring state of Minnesota, where two people have died this month in a deadly immigration crackdown.