Republican front-runner Donald Trump racked up primary wins in the big prize of Michigan and in Mississippi on Tuesday, brushing off a week of blistering attacks from the party's establishment and expanding his lead in the White House nominating race. In the Democratic contest, Bernie Sanders stunned front-runner Hillary Clinton in a narrow Michigan primary upset, giving his upstart campaign new energy. Clinton won in Mississippi, but Sanders' victory is seen as likely to ensure a prolonged fight to pick a candidate for November's general election. (Race to the White House, see graphichere#section-candidates)

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 the brash billionaire's march to the nomination ahead of several key contests next week. The 69-year-old New Yorker built his victories in Michigan, in the heart of the industrial Midwest, and Mississippi in the Deep South with broad appeal across many demographics. He won evangelical Christians, Republicans, independents, those who wanted an outsider and those who said they were angry about how the federal government is working, according to exit polls.

At a news conference afterward, Trump said he was drawing new voters to the Republican Party and the establishment figures who 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 results were a setback for rival John Kasich, governor of Ohio, who had hoped to pull off a surprise win in neighboring Michigan, and Marco Rubio, a U.S. senator from Florida who has become the establishment favorite but lagged badly in both Michigan and Mississippi and appeared unlikely to win delegates in either.

Trump said Rubio's recent attacks on him had backfired. "Hostility works for some people; it doesn't work for everyone," the real estate magnate said at a news conference in Jupiter, Florida. Ted Cruz, a U.S. senator from Texas whose recent victories have positioned him as the prime alternative to the brash billionaire, won the party's primary in Idaho. But Trump suggested his rivals had little hope going forward, and took particular aim at Cruz.