Goals from Aaron O'Connor and Christian Jolley ended Newport's two-match losing run with victory at Southport.
The promotion chasers remain fourth, but have four games in hand on current leaders Kidderminster.
O'Connor and Jolley struck from close range in the first half for Justin Edinburgh's side.
Defeat saw Southport drop to 18th in the table and, apart from bottom side Telford, all those in the relegation zone have games in hand.
Newport are eight points behind second-placed Mansfield and have a game in hand on the Stags.