A series of CBS News/YouGov polls released this week show Sanders leading, and within the margin of error in two early-voting states.
The polls, released on Monday, show Sanders ahead of Hillary Clinton in New Hampshire by 7 points, a lead that has been reflected consistently in many other recent polls.
He trails the former Secretary of State by just 6 points in Iowa. Polls from October put her ahead by as much as 32 points, clearly closing the gap and firming up support since then. That puts Sanders within the 7.6 per cent margin of error.
However, Sanders faces an uphill battle in South Carolina, where he currently trails Secretary Clinton by 47 points, an improvement on the 54-point margin shown by a PPP poll earlier this month. The margin of error on that poll was 8.7 per cent.