The club parted company with the previous incumbent, Alex King, last month after a disappointing start to the season.
Assistant coach Alan Dickens has been doing a dual-role ever since, adding attack coaching to his defensive duties.
But Saints are keen to replace King on a permanent basis and while they have identified possible candidates, others have also contacted them.
“We felt that we needed to make a change because while we had the second best defensive record in the league, we had the second worst attack record,” said Hewitt on King’s exit.
“The simple thing was the we weren’t scoring enough points.
“Alex had been a great servant and worked well at the beginning with us, helping us to win the Premiership and Challenge Cup, but sometimes you have to make a change to bring a new voice in.
“We felt that while we were really grateful for the work Alex had done, we needed to make a change and bring someone new in to rejig our coaching team.
“In the short-term we’ve got (Academy coaches) Paul Diggin and Mark Hopley helping with the first-team and we’ve got a fantastic number of coaches from around the world who have applied and want to come to Northampton Saints.
“We’re talking to those at the moment, with a view to making an appointment in due course.”
And he added: “We let the agents know we’re in the market (for an attack coach) and everyone picks it up anyway in the news.
“We get applications from around the world coming in and people want to work for successful sides like Northampton Saints.”