Northants (312 all out) lead Warwickshire (274-4) by 38 runs.
Jim Troughton and Sam Hain had good days work, as Warwickshire had the better of the second day.
The former, playing his first LV= County Championship game for 12 months due to back problems, made a good 69 and the latter registered his maiden first-class half century as the visitors closed in on the home side’s first innings total.
Warwickshire had begun their reply in serene fashion either side of the lunch interval and three brief interruptions for light rain.
It hasn’t been the best of campaigns for Varun Chopra but he and William Porterfield were in little trouble as they successfully countered the new ball.
The pair had wiped 81 off the deficit before the breakthrough came, the result of a tight spell from Steven Crook who forced Porterfield (32) to fend to second slip.
James Middlebrook, on as early as the 20th over, had been playing an important role at the other end and he was rewarded with the wickets of Chopra (47) and Laurie Evans (6) in quick succession, the former caught behind and the latter stumped to make it 102/3.
That brought in Troughton and he and Hain steadied things to the point that when the tea break arrived it was all level on points.
As the evening session wore on, Warwickshire gradually turned this position on its head and when Troughton hammered Maurice Chambers through extra cover twice in succession to reach his half-century from 75 deliveries, a solid platform for advancement had been established.
While the captain was the dominant partner, Hain lost little in comparison.
His predominantly back-foot style suited the trueness of the surface and he visibly grew in stature as he moved towards what was a maiden half century in the first-class game, a landmark that was achieved from 115 deliveries.
The duo scored 138 between them, before Troughton on 69, rather unnecessarily, attempted to slog-sweep Middlebrook and only succeeded in top-edging to leg slip.
But that was the hosts last success and when the close of play arrived, Hain had moved to within 13 of three figures and his side trailed by only 38.
First thing in the morning, the home side had added 15 to their overnight score of 297 for seven.
Olly Stone (5) edged Chris Woakes to Porterfield at second slip and Rob Newton (114), in an attempt to garner a few quick runs, skied Chris Wright to long-on.