Northampton saw their late play-off push stutter at Sixfields where second half goals from Jason Kennedy and Kyle Dempsey earned Carlisle a 2-0 victory.
The Cobblers had their chances with James Gray's header being saved by Dan Hanford before the Carlisle goalkeeper denied Lawson D'Ath.
Chris Hackett had an effort blocked, Brendon Moloney was off target from the edge of the box and Jason Taylor shot wide.
Carlisle's first chance saw Kennedy head wide just before the break but the visitors improved after the restart with Paul Corry and Dempsey going close.
Moloney fired over for Northampton and Ryan Cresswell headed wide.
Matt Duke was finally called into action to keep out a header from substitute Steven Rigg but the Cobblers keeper was beaten in the 69th minute when Dempsey crossed for Kennedy to score from close range.
Cresswell headed over for the Cobblers before Dempsey doubled Carlisle's advantage in the 71st minute when he headed home a cross from David Amoo.
Gray headed over and substitute Joel Byrom was off target for Cobblers in the closing stages but they never really looked like getting back into the game.
Source : PA