Donald Trump's victory in Iowa, where he trounced a dwindling field of fellow Republicans, cements his position as a seemingly unstoppable force in the race to secure his party's nomination to run for president in November.
Mr Trump won 51 per cent of delegates at Monday night's caucuses, leaving Florida Governor Ron DeSantis and former UN ambassador Nikki Haley scrapping for second place, with Mr DeSantis coming out slightly ahead.
Soon after Mr Trump's landslide win, biotech entrepreneur Vivek Ramaswamy dropped out of the race and endorsed him.
Another long-shot candidate, former Arkansas governor and vocal Trump critic Asa Hutchinson, also pulled out.
After Iowa, Mr Trump has secured the backing of 20 delegates.
He needs 1,215 to lock up the Republican Party nomination, but polling shows he remains the runaway favourite despite facing four criminal prosecutions and other civil cases.
What's next for the Republicans?
After Iowa, all eyes are on New Hampshire, which holds the country's first primary vote next Tuesday.
A repeated win for Mr Trump, 77, could all but seal the Republican nomination to set up his rematch with President Joe Biden in November.
One possible hiccup is that Ms Haley has considerable support in New Hampshire, with some polls putting her within single digits of Mr Trump, who nonetheless remains the favourite.
An upset in New Hampshire would give Ms Haley a huge boost and could open the possibility for her to mount an effective challenge to Mr Trump in other states.
“I really think this is time now for everybody, the country, to come together,” he told a victory rally in Iowa in an unusually conciliatory tone.
But the tycoon and former reality-TV star quickly turned to his usual harsh talk, promising to shut the Mexican border to stop an “invasion” of migrants and pledging to drill for oil if re-elected.
What about Mr Trump's legal cases?
Mr Trump's legal mess – he faces 91 criminal charges in four cases, including some over his efforts to overturn the 2020 election – adds a layer of complication in his bid to return to the White House.
He is using every legal manoeuvre available to try to delay or dismiss the cases, but it remains entirely possible he will be convicted of at least one felony before the November 7 election.
If he were to be convicted and still win the presidency, he might be able to pardon himself.
So far, Mr Trump's legal peril has energised his Republican supporters, who see the prosecutions as politically motivated.
On Tuesday, he was in New York for a civil defamation hearing sparked by a sexual assault case involving writer E Jean Carroll.
“If the election were held today, I think Donald Trump would beat Joe Biden,” pollster Frank Luntz told Bloomberg Television.
The Biden factor
Perhaps the biggest variable in all of this is Mr Biden.
The President, 81, remains deeply unpopular and many polls have him losing against Mr Trump if a match-up were to be held today.
But despite losing support from his own progressive and Arab-American base over his unflinching support for Israel's war in Gaza, Mr Biden hopes a brightening economic outlook will convince Americans to give him a second term.
And although Mr Trump has a lead over Mr Biden in many polls, the former president remains deeply unpopular with large parts of the electorate outside his Republican base.
The election is being closely watched around the globe, with key US allies Ukraine and Israel embroiled in wars and many countries anxious about a return of Mr Trump's “America First” policies.
Donald Trump’s legal woes – in pictures
