Southend lost top spot after a surprise 2-0 loss to Doncaster, with Rovers taking the points thanks to Ricky Ravenhill and Jonathan Forte.
Swansea would have moved above the Shrimpers had they beaten Oldham at the New Stadium, but were held to a goalless draw.
Brentford also missed the chance to close the gap at the top, also playing out a goalless stalemate with bottom club Swindon.
United's 2-2 draw with Rotherham leaves them fifth in the table.
Veteran striker Steve Claridge scored the only goal of the game as Bradford beat Port Vale.
Barnsley came from two goals down to earn a 2-2 draw against Blackpool at Oakwell.
Nottingham Forest moved to within touching distance of the play-offs with a 2-0 win over 10-man Tranmere.
Luke Wilkshire fired Bristol City to 1-0 victory over Tranmere at Ashton Gate.
James Keene came off the bench to hit a dramatic stoppage time winner for Bournemouth at Colchester.
Gillingham and Yeovil drew 0-0 at the Priestfield Stadium, with MK Dons and Chesterfield also failing to find a breakthrough.