Burton Albion had one of two games in hand on the Cobblers on Tuesday night but despite a determined display against promotion chasing Bury went down to a late Shakers strike in a game which saw three players sent off.
The Brewers are still one place and two points behind Northampton at the foot of the table and are only ahead of Barnet, who occupy the final relegation place, on goal difference.
Barnet have been resurgent in recent weeks but lost the man responsible for that revival, manager Martin Allen, on Monday as he accepted the Notts County job.