Bernie Sanders has erased Hillary Clinton's wide lead for the US Democratic presidential nomination, according to a new poll.

Mrs Clinton leads Mr Sanders 48 per cent to 45 among Democratic voters in the Reuters/Ipsos poll.

Democrats had been supporting Mrs Clinton by more than a two to one at the beginning of the year.

The bad news for the Clinton camp comes after she narrowly beat Sanders in the Iowa caucuses and is expected to lose to him in New Hampshire.