Haskell trained fully with the squad and will be available for England's final Rugby World Cup warm-up international.
England manager Martin Johnson will name his side to face Ireland on Thursday lunchtime.
With squad captain Lewis Moody still recovering from a knee injury, Haskell will be in the running to start at open-side flanker, the position he played during England's title-winning Six Nations campaign.
England fielded mix-and-match teams for the games against Wales - but Johnson is looking to field his strongest possible side for the trip to Dublin.
Manu Tuilagi made a try-scoring Test debut in England's victory over Wales at Twickenham earlier this month and he is pushing for a second start.
Although normally considered an outside centre, Tuilagi could emerge as an option for England in the 12 jersey. Shontayne Hape is the only recognised inside centre in England's 30-man World Cup squad.
Johnson must decide whether to stick by Toby Flood, who has been first choice fly-half since the end of the 2010 Six Nations, or reinstall Jonny Wilkinson at number 10.
Whichever decision Johnson makes will set the tone for England, a fortnight before their opening World Cup fixture against Argentina.
England have the option of starting with both Flood and Wilkinson - but that would seem unlikely given Johnson has no other specialist fly-half cover.
Loosehead prop Andrew Sheridan is in line to make his first appearance of the warm-up campaign after recovering from summer shoulder surgery.
As well as Moody, England will be without Ben Youngs in Dublin as the Leicester scrum-half continues his comeback from knee surgery.
Joe Simpson, selected as England's third scrum-half behind Youngs and Richard Wigglesworth, is set to make his Test debut at the Aviva Stadium.
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