London - Eoin Morgan would love to add the Twenty20 World Cup trophy in Australia next year to the 50 over version he skippered England to victory in July but he told the BBC it would depend on clearing up a persistent back problem.
The 32-year-old Irishman had problems with his back during the drawn-out World Cup campaign - going off early in the game against the West Indies with a back spasm.
Morgan - who recovered to hit a ODI record of 17 sixes four days later against Afghanistan - pulled out of a match with Sussex last week due to further trouble with his back.
Morgan - who was at Lord's to receive a commemorative cap for his World Cup success over New Zealand, playing 200 one-day internationals for England and captaining them on 100 occasions - said he wanted to captain them but could not commit yet.
"I need more time to think. It's a big decision and a big commitment," he said.
"I just don't want to let anybody down. When you lead, you have to lead from the front and you have to be physically fit.
"Finding form is another thing. Hopefully that works itself out."
Morgan, who played for Ireland at the 2007 ODI World Cup but had always wanted to play Test cricket for England, the land of his mother's birth, and eventually did so in 2010, said he wanted the problem dealt with as quickly as possible to leave him time to recover.
"I need time," said Morgan.
"I need the season to end pretty soon so I can have that time to physically get fit and guarantee it's not an injury risk between this year and next, then I can make a call on it."
England's next limited overs commitment is five T20 internationals on their tour of New Zealand in November.
The 50-over side do not play until they tour South Africa in February.