ANNAPOLIS, JAN. 10 -- One of the biggest clubs Gov. William Donald Schaefer holds over the Maryland General Assembly this year is his influence over the politically explosive issue of redrawing legislative district lines.

State Senate leaders today began whittling away at that weapon. The Rules Committee voted to make it easier for leaders to pass their own plan for redistricting; otherwise, they would have to accept one devised by Schaefer.

The rule change would mean that only 29 of the 47 senators would have to give their approval to cut off debate on redistricting bills, instead of the 32 now required. The easier it is for the Senate to halt debate, the better the chances of lawmakers passing their own plan.

It's a seemingly minor change, but one that Senate Minority Leader John A. Cade (R-Anne Arundel) warned could "lead to the destruction of the unlimited debate rule, which was designed to protect the interests of all minorities." Cade cast the lone dissenting vote in committee. The full Senate will vote on Tuesday.

Even the small change makes a critical and personal difference to legislators, some of whom may see their districts disappear as a result of population shifts recorded in Maryland by the 1990 census. Planning for the intricate process is the strong undercurrent of the current legislative session.

Maryland's constitution allows the governor to submit his own plan for changing legislative districts when the General Assembly convenes in January 1992. If the legislature doesn't pass a redistricting bill within 45 working days, the governor's proposal becomes law.

Because a filibuster in the Senate appears virtually inevitable, lawmakers said, the governor would have outsized influence. "This is an issue that's closest to our hearts," said Sen. John A. Pica Jr. (D-Baltimore), chairman of the Senate committee that will oversee plans for redistricting.

A spokesman for Schaefer dismissed the proposal to lower the filibuster cutoff number as a parliamentary move and said it did not appear to be directed at the governor.

But lawmakers are wary of the influence Schaefer can use over redistricting and of his ability to use that power to persuade lawmakers to his position on other legislation.

Almost nothing roils a legislative body more than redistricting. Because of the latest census, boundary lines must be redrawn this fall on Maryland's eight congressional districts. But the real battle will be over the boundary lines of the 47 legislative districts. Population shifts will mean that Baltimore could lose as many as two senators and six members of the House of Delegates. Suburban counties are expected to gain representation in the 188-member General Assembly.

Senate President Thomas V. Mike Miller Jr. (D-Prince George's) said he has no reason to believe that Schaefer's past battles with lawmakers would lead to "punitive" decisions on new legislative districts.

But, he added, "It is true there are legislators who have expressed disfavor with the governor in {the} past who are not among his confidantes."