The US Democratic Party has voted to prioritise minority-heavy states in its kick-off of 2028 presidential primaries, opening the nominating calendar in South Carolina and Nevada.

The new schedule "truly represents our party and our values and will help us retake the White House in 2028," party chair Ken Martin said in a statement.

South Carolina, a south-eastern state with a large African American population, will vote on 22 January 2028.

The western state of Nevada, which is more than 30 percent Latino, will follow on February 1.

New Hampshire, New Mexico, Michigan and Virginia round out the first six states to choose the party's nominee for the White House race.

The Democratic Party said the new schedule aims to test White House hopefuls by exposing them to a more diverse electorate, as well as key states in the general election.

Shifting early-state dynamics

South Carolina played a pivotal role in Joe Biden's successful bid for the Democratic nomination in 2020.

After becoming president, he returned the favour by changing the rules to make South Carolina the first primary of the 2024 campaign.

However, New Hampshire — where state law mandates that it be the first state in the country to hold a primary — defied the new rules and held its vote before South Carolina.

To deter such actions, party officials voted on Saturday to increase penalties for states that do not comply with the designated schedule.

It was unclear if New Hampshire will follow the new schedule.

The situation also remained uncertain for Iowa, where state law requires caucuses — an alternative form of voting — to take place before any other state.

Compared to South Carolina or Nevada, previous early-voting states New Hampshire and Iowa have smaller and less diverse populations.

Over 90 percent of New Hampshire's population of 1.4 million is white, and 88 percent of Iowa's population of 3.2 million is white, per the US Census.