The Iowa Democratic Party says results from the state’s first-in-the-nation caucus have been delayed due to “quality checks” and new reporting rules.

US correspondent Charles Croucher told Heather Du Plessis-Allan the complicated voting system is slowing things down.

"I've never seen a more complex and more diffcicult process than the one here in Iowa."

Nearly a dozen Democratic White House contenders are still vying for the chance to take on Trump in November.

Iowa's first-in-the-nation caucuses have been expected to provide some clarity for what has been a muddled nomination fight.

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