Rob Keogh posted his maiden double century for Northamptonshire before Jimmy Adams led a determined Hampshire reply on day two at the Ageas Bowl.
Hampshire captain Adams ended a run of poor personal form with an unbeaten 71 as Hampshire closed on 160-2 , in reply to Northamptonshire's 438.
Hampshire still trail by 278 runs and need another 129 to avoid the follow-on but the wicket, so difficult on the first morning, has flattened out in the sunshine and there was little to encourage the bowlers on either side.
Northamptonshire, needing every point to close the gap on leaders Lancashire, resumed the second day at a healthy 323-6 and it was another 18 overs before Hampshire finally ended a morale-sapping stand of 187 for the seventh wicket between the inexperienced Keogh and Matt Spriegel.
Spreigel had hit eight fours in his 76 when he drove across an outswinger from James Tomlinson and wicketkeeper Michael Bates held the catch, only for Northamptonshire to continue the process of grinding down the opposition.
Trent Copeland went to a Bates leg side catch at 387 to give new pace bowler Ruel Brathwaite something further to celebrate, his third wicket of the innings coinciding with the signing of a contract with Hampshire to the end of next season.
Keogh and Jon Batty added another 51 for the ninth wicket before both departed in the space of eight balls, Batty giving Bates his sixth catch of the innings and Keogh's almost eight-hour vigil coming to an end when he gave Liam Dawson a return catch.
Keogh, whose previous best score had been 44, faced 383 balls and included 32 fours. He fully deserved his standing ovation from the small crowd and both sets of players having come to the crease when batting was at its most difficult and when the visitors were in trouble on 24-3.
Michael Roberts and Adams began the task of replying but the former was the first to go for 36, beaten for pace by Steven Crook - but a partnership of 97 for the second wicket between Adams and Dawson allayed fears of a Hampshire collapse, coming to grief only at 133 when Dawson hoisted Spreigel's off spin to Copeland at midwicket where the Australian held a steepling catch.
Neil McKenzie was 22 not out at the close with a draw looking increasingly likely.