The extension was given as Selig gathered with the owners to discuss the sticky issue of contraction. Owners voted November 6 to eliminate two teams, but did not name them.
The likely candidates are the Montreal Expos and the Minnesota Twins. Carrying out the plan became more difficult after a Minnesota judge issued a temporary injunction that forced the Twins to fulfill their lease next season at the Metrodome.
The owners were not expected to make any final decision on contraction at Tuesday's meeting.
The contraction plan comes as baseball also tries to negotiate a new collective bargaining agreement with the Players' Association. Past negotiations often stalled, and the players staged a strike in 1994 that resulted in the cancelation of the World Series.
The 67-year-old Selig is credited with bringing baseball back to Milwaukee in 1970 when he purchased the Seattle Pilots and moved them to Wisconsin. He is the first former owner to become commissioner.
Under his watch as commissioner, baseball introduced the three-division format, interleague play and the addition of the wild card.
His daughter, Wendy Selig-Prieb, now runs the Brewers.
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