US Democratic presidential candidate Hillary Clinton has declared victory in the Kentucky primary as she moves nearer the presidential nomination.

The former secretary of state won the state by half a percentage point with nearly all the votes counted. Meanwhile, Sanders won the Oregon Democratic primary,bagging 53 per cent votes to her 47 per cent.

Front-runner Clinton is almost certain to secure the nomination in July, with a significant delegate lead.

The Kentucky Democratic primary will award 60 delegates to go to the party’s convention in Philadelphia while Oregon’s primary will award 74.

In the Republican race, Donald Trump won the party’s only contest on Tuesday in Oregon, which was no surprise as he was the only candidate left in the race.