The Chelsea winger has not played for the Three Lions since last year's World Cup and was once again omitted by Southgate for the team's final Euro 2024 qualifiers against Malta and North Macedonia, although the coach explained that it was hard to make room for the star.
He said: "The door is 100 per cent open not only for Raheem but for other players in this squad.
"There’s no doubt about that. We don’t need to know about his quality, his personality. He is a crucial part of why we’ve had the journey we’ve had over the last few years. I can only repeat what I’ve said in the last few squad selection meetings: the team are playing really well.
"We had an exceptional win against Italy last time around. Who do we leave out to put him in? It is as simple as that really."
Southgate denied suggestions that Sterling had upset him and explained that he was reluctant to change the squad that sealed England's spot at next summer's tournament last month.
The manager said: "He wasn’t available in March or June so the team had started on a good run. We won in Italy for the first time in 60 years. The two performances in June were excellent. We’ve stuck with that group pretty much through this qualifying campaign.
"We’ve deliberately not made many changes because we felt that’s been fair to the guys who have been in the squad. Performances have been excellent. There is huge competition for places. There is no question Raheem is looking dangerous for his club. He looks invigorated since the start of this season."