Everton manager Roberto Martinez believes it is "impossible to say" whether Tim Howard will remain with the club next season.
Howard is under contract at Everton until 2018 but his backup Joel Robles has earned plaudits for recent cup wins, and Martinez couldn't rule out a move away from Goodison Park this summer for the United States international.
Asked if Howard would still be with Everton next season, Martinez said, "It is impossible to say that. We need to take it game by game and week by week.
"I want Tim to feel stronger in every game. Watching him in training, I don't see a sign of weakness or him being worn down or tired. It is the opposite. "He is up for the challenge, up for helping the team and keeping up standards. I'm sure every experience will affect what you want to do in the summer.
Howard has reacted to some jeers from the Everton fans in recent weeks after the team lost home Premier League games to Leicester and Stoke City.
Meanwhile, his fellow keeper Joel Robles has led Everton to wins in the Capital One Cup semifinal and FA Cup third round.
But ahead of Howard's return to goal against Manchester City on Wednesday, Martinez backed the United States international.
"I don't think he was being sarcastic," Martinez of Howard's interactions with fans. "He cares about our football club and has an incredible attachment to it. He is trying to interact with the fans with the experience he has.
"Tim would never blame a defender for his mistake and I appreciate that. Tim has got 350 appearances in the Premier League which is a record for Everton. He is part of our club and our badge.
"He had mistakes but he had big moments. We need to be more understanding that sometimes you're going to get that.
"His day-to-day work shows me the strength, power and positive effect he has on young players. I feel we are a stronger team with Tim Howard in the dressing room."
Everton take on Manchester City on Wednesday for the second time in seven days after last week's 2-1 win in the first leg of the Capital One Cup semi-finals, and Martinez said he was not willing to look beyond the next game.
"We shouldn't look that far away," he said. "We are here with a real focus of winning on Wednesday. That is all that matters.
"We have a incredible squad, a group of players here that I'm excited about and I'm looking forward to seeing them develop and Tim Howard is a big part of that.
"Whatever happens at the end of the season you cannot guess it now and it would be wrong to try to guess that."