Donald Trump and Joe Biden have swept the Super Tuesday races that have been called so far.
Both Mr Biden and Mr Trump claimed early victories in Virginia, North Carolina, Tennessee, and Oklahoma.
Super Tuesday is the biggest date in the primary calendar – voters in 16 states and one territory go to the polls.
As it stands, Donald Trump looks all but certain to be the Republican Party’s presidential candidate once again, having already chalked up big wins in Iowa, the US Virgin Islands, North Dakota, New Hampshire, Nevada, South Carolina, Michigan, Idaho, and Missouri.
Only the well-funded but under-performing ex-UN ambassador Nikki Haley remains to challenge him.
Ms Haley and Mr Trump were neck and neck in Vermont as votes were counted on Tuesday night.
She did pick up a much-needed win in Washington DC’s primary on Sunday.
The Democratic contest is even more one-sided, with Mr Biden seemingly set to be his party’s candidate again as he seeks a second term in the White House.