NEW YORK -- Matt Stover, the Baltimore Ravens' veteran kicker, has begun a campaign to replace Gene Upshaw as executive director of the NFL Players Association by next March.

Stover's action comes at a time when the union could be heading for critical negotiations with the league on the collective bargaining agreement.

"I feel that the board must begin to prepare for a change in leadership immediately," Stover said in an e-mail to the union's executive board and player representatives that was obtained Tuesday by ESPN. "I believe we have the proper environment with our teammates and leadership within the board to execute the process of this selection."

Union president Kevin Mawae of the Tennessee Titans said that Stover's opinion does not reflect the opinion of the players.

Upshaw, whose contract runs through 2010, has said he will not leave until the union gets through its latest negotiations with the owners, who are expected to opt out of their March 2006 agreement with the union next November. That would trigger a new round of negotiations.

March 2009, the beginning of the last year with a salary cap if the contract is voided, could be a critical time in those talks.

The 40-year-old Stover, entering his 19th NFL season, said in a statement issued by the Ravens that it was not his intention for his e-mail to be made public.

"I'm going to respect the process of our union leadership, executive committee and player reps," he said in a statement issued by the Ravens. "I choose to handle this matter privately. It was certainly not my intention for my private email to a select group to become public."

Mawae, elected last month as the union's new president, dismissed Stover's letter.

"Matt Stover's letter does not reflect the view of the entire executive committee or the board of player representatives," he said in a statement issued by the union. "The board is in the process of preparing for the possibility of a work stoppage and understands the importance of having Gene, with his experience and history, lead the direction of the NFLPA."

Added former NFLPA president Troy Vincent: "It's absolutely ridiculous."

Copyright 2008 by The Associated Press