A disputed penalty put Tranmere on the road to a 4-0 win - their 13th home victory of the season - to keep their play-off hopes alive and relegate Northampton.
The result was harsh on a spirited Northampton. It was their 14th away reverse and condemned them to Division Three football next season.
The visitors were not without their chances in the opening half. John Achterberg in the home goal did well to turn aside a 17th minute effort by Paul Harsley and substitute Marco Gabbiadini blazed over in the 35th minute.
Gabbiadini had replaced the injured Tom Youngs after only five minutes and there was further woe for the Cobblers when Jerry Gill was stretchered off after 65 minutes.
Lee Harper in the visiting goal made a terrific fingertip save to keep out a Tyrone Loran header in the 24th minute, while Gareth Roberts' powerful shot for the Merseysiders was deflected inches wide a minute later.
Tranmere won a penalty on 58 minutes when Town skipper Ian Sampson was judged to have held down Simon Haworth following a free-kick.
Shane Nicholson fired a left-footed penalty into the left-hand corner of the net.
Tranmere doubled their lead two minutes later. Haworth's angled shot should have been cleared by a clearly despondent Sampson but he watched the ball trickle over the line.
Rovers took complete charge from then onwards. Haworth headed against the bar on 82 minutes, and in the 89th minute Iain Anderson blasted home from close range from a Jason Price cross.
A minute later Alex Hay grabbed his first goal with an angled shot from 12 yards when set up by Mickey Mellon to make it four.
Tranmere boss Ray Mathias was pleased with his players performance.
He said: "We needed a kick start at half time and the penalty put us on a roll. We went on to control the game and created a lot of chances.
"You can only keep winning and hoping. We have not had many penalties but you are glad when you get one. The referee saw something which was obviously wrong." Opposite number Martin Wilkinson was unhappy over the decision. "It was soft and cost us. My man tried to win the ball fairly and you cannot take the physical contact out of the game. But then our concentration went.
"We can sit and make all the excuses in the world but it won't help. We have got to look forward and rebuild the team.
"In the first half we did well again but then it was the same old story - we collapsed like a pack of cards."