Republican front-runner Donald Trump rolled to primary wins in the big prize of Michigan and in Mississippi on 8 March, brushing off a week of blistering attacks from the party's establishment to expand his lead in the White House nominating race. Trump's convincing win in Michigan restored his outsider campaign's momentum and increased the pressure on the party's anti-Trump forces to find a way to stop his march to the nomination ahead of several key contests next week.

"This was an amazing evening and I don't think I've ever had so many horrible, horrible things said about me in one week. Thirty-eight million dollars-worth of horrible lies," Trump said in Jupiter, Florida.

Trump built his victories in the industrial Midwest and the Deep South with broad appeal across many demographics, winning evangelical Christians, Republicans, independents, those who wanted an outsider and those who said they were angry about how the federal government is working, exit polls showed.

At a news conference, Trump said he was drawing new voters to the Republican Party and the establishment figures that are resisting his campaign should save their money and focus on beating the Democrats in November.

"I hope Republicans will embrace it," Trump said of his campaign. "We have something going that is so good. We should grab each other and unify the party."

The Michigan victory sets Trump up for a potentially decisive day of voting on 15 March, when Ohio, Florida, Illinois, Missouri and North Carolina – like Michigan, states rich in the delegates who will select their party's nominee at July's Republican National Convention – cast ballots.

The Republican contests in Florida and Ohio award all the state's delegates to the winner. If Trump, 69, could sweep those two states and pile up delegates elsewhere next week, it could knock home-state favourites Marco Rubio and John Kasich out of the race and make it tough for Ted Cruz to catch him.