Northampton failed to extend their lead over the teams at risk of relegation as they lost 2-0 at home to Blackpool.
Goals from Ashley Fletcher, who scored his fifth goal in the last eight games, and Niall Ennis put Blackpool in the lead, leaving Northampton six points above the relegation zone in 19th position.
Blackpool dominated the first half and had a good opportunity to score with Sonny Carey, but he missed the target and hit the side-netting.
After 20 minutes, Blackpool broke the deadlock when Rob Apter provided a perfect cross for Fletcher to score with a header.
Northampton tried to respond with long-range attempts from Sam Hoskins and Tyler Roberts, but they were unsuccessful in creating clear chances.
At the beginning of the second half, Aaron McGowan and Timothy Eyoma made important goal-line clearances to deny Ennis and Fletcher, but Blackpool eventually sealed the victory.
Blackpool took advantage of a defensive mistake just after the one-hour mark, allowing Ennis to score confidently and secure the three points for his team.