Hillary Clinton feels the Bern as Sanders snatches surprise Michigan win
Donald Trump swept to victory in Mississippi and Michigan
Socialist Bernie Sanders has breathed new life into his long-shot White House bid with a crucial win in Michigan's presidential primary, chipping away at Hillary Clinton's dominance in the Democratic race.
Meanwhile Republican front-runner Donald Trump swept to victory in Mississippi and Michigan, deepening his grip on his party's nominating contest despite fierce efforts to blunt his momentum.
Mrs Clinton easily carried Mississippi for her party, but was defeated in white, working-class Michigan, where voters expressed concerns about trade and jobs, by Mr Sanders.
Mr Sanders said he was "grateful to the people of Michigan for defying the pundits and pollsters" and delivering him a win.
"We came from 30 points down in Michigan and we're seeing the same kind of come-from-behind momentum all across America," he said.
He said Michigan signalled that his campaign "is strong in every part of the country, and frankly we believe our strongest areas are yet to happen".
But even with Mr Sanders' win, Mrs Clinton and Mr Trump moved comfortably closer to a general election face-off.
Mrs Clinton breezed to an easy victory in Mississippi, propelled by overwhelming support from black voters, and now has more than half the delegates she needs to clinch the Democratic nomination. Mr Trump, too, padded his lead over Texas senator Ted Cruz, his closest rival.
The front-runners turned their sights on November as they revelled in their victories.
"We are better than what we are being offered by the Republicans," Mrs Clinton declared.
And in a nod towards the kind of traditional politics he has shunned, Mr Trump emphasised the importance of helping Republican senators and House of Representatives members get elected in November.
Having entered Tuesday's contests facing a barrage of criticism from rival candidates and outside groups, he also delighted in overcoming the attacks.
"Every single person who has attacked me has gone down," Mr Trump said at one of his Florida resorts.
While a handful of recent losses to Texas senator Ted Cruz have raised questions about Mr Trump's durability, Tuesday's contests marked another lost opportunity for rivals to slow his march.
Next week's winner-take-all primaries in Ohio and Florida loom especially large as perhaps the last chance to stop Mr Trump short of a long-shot contested convention fight.
Ohio governor John Kasich was in a fight for second place in Michigan and hoping a good showing would give him a boost heading into next week's crucial contest in his home state.
Florida senator Marco Rubio, a favourite of Republican elected officials, continued to struggle on Tuesday, upping the stakes for him at home on March 15.
If Mr Rubio and Mr Kasich cannot win at home, the Republican primary appears set to become a two-person race between Mr Trump and Mr Cruz, an uncompromising conservative.
The Texas senator is sticking close to Mr Trump in the delegate count and with six states in his win column, he's argued he is the only candidate standing between the brash billionaire and the Republican nomination.
During a campaign stop at a North Carolina church, Mr Cruz blasted Mr Trump for asking rally attendees to raise their hands and pledge their allegiance to him. He said the move struck him as "profoundly wrong" and something "kings and queens demand" of their subjects.
"I'm not here asking any of you to pledge your support of me," Mr Cruz said, to thunderous applause and cheers. "I'm pledging my support of you."
The economy ranked high on the list of concerns for voters heading to the polls in Michigan and Mississippi. At least eight in 10 voters in each party's primary said they were worried about where the American economy was heading, according to early exit polls conducted for The Associated Press and television networks.
Among Democrats, eight in 10 voters in both states said the country's economic system benefits the wealthy, not all Americans.
Mr Sanders has sought to tap into that concern, energising young people and white working-class voters with his calls for breaking up Wall Street banks and making tuition free at public colleges and universities.
Michigan, with big college towns and a sizeable population of working-class voters, should be a good fit for him, But Mrs Clinton has led in polling.
The results in Mississippi underscored her overwhelming strength with black voters and Mr Sanders' stunning inability to draw support from a constituency crucial to Democrats in the general election.
Mrs Clinton carried nearly nine in 10 black voters in Mississippi, mirroring her margins in other southern states with large African-American populations.
She has now accumulated 1,214 delegates and Mr Sanders 566, including superdelegates - members of the US Congress, governors and party officials who can support the candidate of their choice at the convention. Democrats need 2,383 delegates to win the nomination.
With Tuesday's wins, Mr Trump leads the Republican field with 428 delegates, followed by Mr Cruz with 315, Mr Rubio with 151 and Mr Kasich with 52. Winning the Republican nomination requires 1,237 delegates.
Meanwhile, Mr Cruz won the Republican presidential primary in Idaho, adding a seventh state win to his tally.
Results from the Republican caucuses in Hawaii are expected later.