England coach Clive Woodward has told his players they must committo the three-Test tour of Australia and New Zealand in June if they want toplay in this season's Six Nations and the 33-year-old Johnson is reportedlyunwilling to make that commitment.
Johnson is to discuss his decision with Woodward this week. England open their defence of the championship against Italy inRome on Feb 15.
He has captained England 39 times during his 84 Tests, and playedin the Five Nations Grand Slam in 1995 and Six Nations Grand Slam in 2003. He made his debut for England with a win against France atTwickenham in
Woodward was reported to have drawn up a shortlist to replaceJohnson as captain that does not include fly-half star Jonny Wilkinson.
They are former skipper and No 8 Lawrence Dallaglio, scrum-halfMatt Dawson, blindside flanker Richard Hill and prop Phil Vickery.
Dallaglio, who was Johnson's predecessor as England captain,admitted he would love to regain his position if Johnson retires. Dallaglio held the post until drug revelations, which he denied,forced him to step down in 1999.
"I'm fairly realistic and philosophical about it," he said, "Form is going to be the most decisive factor in any decisionand I am playing well."