Republican Donald Trump has won two more states, Michigan and Mississippi, in his bid for the White House.
In the Democratic race, Bernie Sanders had a surprise victory in Michigan, but Hillary Clinton increased her lead with a big Mississippi win.
The Republicans are also voting in Idaho and Hawaii.
The four state contests on Tuesday help choose the candidates from each party who will compete in November's presidential election.
It was a terrible night for Republican Florida Senator Marco Rubio, who came in a distant fourth in both Michigan and Mississippi, days before his must-win contest in his home state.
Election results - as they come in
Mr Trump, a businessman with no experience of elected office, leads the polls in Florida, from where he delivered his victory speech on Tuesday night.
"One of the things I am most happy about is the turnout has been just massive… I think it's the single biggest story in politics today," he said at a press conference in Jupiter.
In the Democratic race, Bernie Sanders had a surprise victory in Michigan, but Hillary Clinton increased her lead with a big Mississippi win.
The Republicans are also voting in Idaho and Hawaii.
The four state contests on Tuesday help choose the candidates from each party who will compete in November's presidential election.
It was a terrible night for Republican Florida Senator Marco Rubio, who came in a distant fourth in both Michigan and Mississippi, days before his must-win contest in his home state.
Election results - as they come in
Mr Trump, a businessman with no experience of elected office, leads the polls in Florida, from where he delivered his victory speech on Tuesday night.
"One of the things I am most happy about is the turnout has been just massive… I think it's the single biggest story in politics today," he said at a press conference in Jupiter.
