England will fly out to Denver on Saturday with a 45-man squad to continue their Rugby World Cup preparations.
Following three weeks at Penyhill Park, their schedule continues with two weeks at Rugby Town USA in Glendale, Colorado.
Elliot Daly (Wasps), Maro Itoje (Saracens), Stephen Myler (Northampton Saints) and Ed Slater (Leicester Tigers) will return to their clubs and be on standby.
Meanwhile, Nick Easter will remain at Harlequins for treatment on a sore back and will rejoin the squad at Pennyhill Park on Sunday, 2 August following their post-Denver break.
“Elliot and Maro have fitted in and trained well and it’s been great for them to be in this environment," said England head coach Stuart Lancaster.
“They are both young players who have bright futures. They have made a great impression and I am sure other opportunities will come for both of them further down the line.
“Steve and Ed, likewise, have contributed greatly. Ed has done well to recover from his knee injury having missed the majority last season. However, there is a lot of competition in the second row.
“Steve, who is in another really competitive position, has only recently been able to take a full part in training having injured his knee towards the end of last season.
“But he is getting up to speed now and I am sure he would be ready to come back in should the opportunity arise.
“I have spoken to all the players to explain that things can change very quickly and they can come back in at any point.
“Nick will stay for treatment on his back rather than risk aggravating it further with travel and we look forward to him rejoining the squad in August when we will review the squad and also consider those who have been unable to begin the camp after suffering injuries at the end of last season.
“The players have worked very hard for the past three weeks and there is a really good feel about the group. Denver is the next stage in our training, a chance to develop further in a different environment.”
England training squad:
Chris Ashton (Saracens), Dave Attwood (Bath Rugby), Brad Barritt (Saracens), Kieran Brookes (Northampton Saints), Mike Brown (Harlequins), Luther Burrell (Northampton Saints), Sam Burgess (Bath Rugby), Danny Care (Harlequins), Danny Cipriani (Sale Sharks), Calum Clark (Northampton Saints), Dan Cole (Leicester Tigers), Alex Corbisiero (Northampton Saints), Luke Cowan-Dickie (Exeter Chiefs), Lee Dickson (Northampton Saints), Kyle Eastmond (Bath Rugby), Owen Farrell (Saracens), George Ford (Bath Rugby), Alex Goode (Saracens), Jamie George (Saracens), James Haskell (Wasps), Jonathan Joseph (Bath Rugby), Courtney Lawes (Northampton Saints), Joe Launchbury (Wasps), George Kruis (Saracens), Matt Kvesic (Gloucester Rugby), Joe Marler (Harlequins), Jonny May (Gloucester Rugby), Ben Morgan (Gloucester Rugby), Matt Mullan (Wasps), Jack Nowell (Exeter Chiefs), Geoff Parling (Exeter Chiefs), Chris Robshaw (Harlequins), Semesa Rokoduguni (Bath Rugby), Henry Slade (Exeter Chiefs), Billy Twelvetrees (Gloucester Rugby), Mako Vunipola (Saracens), Billy Vunipola (Saracens), Anthony Watson (Bath Rugby), Rob Webber (Bath Rugby), Richard Wigglesworth (Saracens), David Wilson (Bath Rugby), Tom Wood (Northampton Saints), Marland Yarde (Harlequins), Ben Youngs (Leicester Tigers), Tom Youngs (Leicester Tigers).