Shawcross is back in Stoke's squad for Sunday's tough trip to face title challengers Chelsea in the Premier League.
He has been out since late February after serving a three-match ban for a red card picked up against Arsenal and then suffering a couple of niggling injuries.
Now he has just four games left to force his way into Fabio Capello's thinking, having been called up for the last England match, on the day he was sent off against Arsenal.
The former Manchester United youngster will probably not even make the starting-line up at Chelsea but Pulis still believes he has a chance of going to South Africa.
He said: "He has trained well all week and is certainly in contention, but I have not decided yet whether to put him straight into the side."
However, that reluctance does not affect Pulis' opinion of the player. He said: "Ryan is one of the best young players in the Premier League in his position, no-one will convince me otherwise.
"He is one of the young players that we will be building this club around over the next five four or five years or so.
"He has already captained this club as a youngster, and I certainly see him as a future long-term captain of Stoke.
"I still think he can make the England World Cup squad, it is still very open and there are always a few injuries at the end of the season so he still has a great chance of being involved, as has Matthew Etherington.
"If I was picking the team then Ryan would go, but I am not picking it, that is up to Fabio Capello. I won't tell him what to do or not to do.
"That is up to him. But as a young player then Shawcross has got what it takes."
Shawcross said: "Scouts come to every game (for England) so if you are playing well, they will find out.
"But with Chelsea going for the title, it will be a big game for everyone. I am available but it is up to the manager.
"I have been out for a long time, and I need to get back playing. I would have to say that my England chances are a bit slim at the moment, but I have not given up."
For Pulis it is a chance to see his side pitched against the country's best two sides in the title run-in. Stoke also have to visit Manchester United on the last day of the season.
Pulis said: "I have said that Chelsea would win the title, certainly a few weeks ago I felt that. But they have had a hiccup and Manchester United are still there.
"Chelsea may be missing John Terry, who is suspended, but they could have Ashley Cole back on Sunday and he is a an outstanding player. They have missed him.
"It is all to play for. It is whoever holds their nerve best now. Both teams have been there before, they've both won the title so there is no lack of experience within the title race, you are not facing a situation where one side is finding it all a bit different. They both know what it takes.
He added: "We are delighted to be at this stage of the season and know we are safe, and we would desperately want to top it off by getting enough points to better last season's tally. One more win would do it.
"At Chelsea we must make sure we give a good account of ourselves. And we must hope a few decisions from the referee to go our way, not all but certainly some against one of the big four clubs. That does not always seem to happen for the smaller clubs."