Eddie Jones says it is 'extraordinary' what Dylan Hartley has done for his country in recent years.
And the England boss has backed the Saints skipper to come back with 'intent and dedication' following his spell on the sidelines with concussion.
Hartley has not played since the Six Nations clash with Ireland on March 17.
His most recent game for Saints was at Saracens on January 20 as he was forced to sit out the closing stages of the season due to concussion.
He will also miss England's tour of South Africa this summer.
But Hartley has more than contributed for the Red Rose in recent years, captaining them to successive Six Nations titles in 2016 and 2017.
"You never know - nature decides when the player can come back, he just needs to wait and see," said Jones when asked about a possible return for Hartley.
"If he's right to play, he'll play. He'll come back with intent and dedication, and he's got to fight to get his place back in the England side.
"If he doesn't come back, he'll be remembered as the most successful captain England's ever had. Look at his winning percentage, it's higher than any other Test captain.
"It's extraordinary what he's done for this country, and it's extraordinary the criticism he attracts."
Jones added that Hartley was not sure when he would be back in action.
"He doesn't know - he's relying on the doctors to give him the all-clear," Jones said.
"He's got the best medical care, and he'll have to fight for his place when he's back.
"He's okay, he understands. He can't control injury. He's just got to keep his focus on staying as fit as he can. He's 100 per cent determined to be back."