US Republican candidate Donald Trump has won the South Carolina Republican primary, while Hillary Clinton has won the Nevada Democratic caucuses.
The victories put both Ms Clinton and Mr Trump in strong positions as the 2016 presidential election nears the March 1 Super Tuesday contests, a delegate-rich voting bonanza.
CNN's David Chalian says Mr Trump's victory can't be underestimated.
"Donald Trump is on the path to become the Republican nominee for president – more so than any other candidate in the race. That is what is happening here."
Mr Trump's performance could unnerve the Republican establishment, as South Carolina has sided with the eventual nominee in every GOP presidential race since 1980, apart from in 2012.
Republican candidate Jeb Bush has pulled out of the White House race following Mr Trump's latest success.
Ms Clinton's roughly five-point win eased the rising anxieties of her backers, who have been concerned by the growing challenge from fellow Democratic candidate Bernie Sanders. At a victory rally in Las Vegas, she praised her supporters and declared: "This one is for you. I want to thank each and every one of you. You turned out in every corner of this state with determination and purpose – hotel and casino workers who never waiver."
For both Republicans and Democrats, the 2016 election has laid bare voters' anger with the political establishment and the influence of big money in the political system. The frustration has allowed Mr Sanders and Mr Trump openings while leaving more traditional candidates scrambling to find their footing.
Mr Trump's latest victory comes after a week in which he threatened to sue one of his rivals, accused former US President George W Bush of lying about the invasion of Iraq and engaged with a war of words against Pope Francis. His victory is another sign that the conventional rules of politics don't seem to apply for the brash billionaire reality TV star.