(Reuters) - Celebrity real estate developer Donald Trump has extended his lead nationally over Senator Ted Cruz of Texas and Ohio Governor John Kasich for the Republican presidential nomination, according to the latest Reuters/Ipsos poll.

The national online poll from April 4 to 8 showed that 42 per cent of Republicans support Trump, compared with 32 per cent for Cruz and 20 per cent for Kasich.

Trump has topped the poll of Republican voters since July, though his lead narrowed considerably in recent weeks as Trump retweeted unflattering pictures of Cruz's wife and his campaign manager was charged with battery in an incident involving a reporter at a campaign event.

Meanwhile, former Secretary of State Hillary Clinton led Senator Bernie Sanders of Vermont for the Democratic nomination. The poll showed that 53 per cent of Democrats support Clinton and 43 per cent support Sanders.

The poll included 626 Republicans and 668 Democrats and has a credibility interval of 4.6 percentage points.