Billionaire Donald Trump won the Republican presidential caucus in Kentucky on Saturday, his second victory of the night in the nomination contest after Louisiana, US media said.

Billionaire Donald Trump won the Republican presidential caucus in Kentucky on Saturday, his second victory of the night in the nomination contest after Louisiana, US media said.

His nearest rival, Senator Ted Cruz, decisively won two contests in Kansas and Maine.

Trump's victories thwart a concerted effort from Republican Party elders to slow his advance toward the White House nomination.