WASHINGTON (AP) _ A Senate panel today postponed until next week a vote on on William Lucas' nomination to be the Justice Department's civil rights chief after an undecided member said he wanted to study new information about Lucas.

Sen. Howell Heflin, D-Ala., whose vote could decide whether or not the Senate Judiciary Committee endorses Lucas, asked for the delay because of material ''that has come to my attention in the last few hours.''

Heflin did not describe the information, but he later indicated that if forced to vote today he might not have joined the panel's Republicans in supporting Lucas to be assistant attorney general for civil rights.

''I'm prepared to vote - it may not be the way you want me to vote,'' Heflin told Sen. Strom Thurmond, R-S.C.

Sen. Joseph R. Biden Jr., D-Del., the panel's chairman, rescheduled the vote for next Tuesday morning, saying there would be no further delays in committee action on Lucas' nomination.

Republican supporters of Lucas, a black Republican from Detroit with a background in law enforcement, voiced concern that a further delay would likely prevent the full Senate from taking up the nomination until after its summer recess, which begins Aug. 4.

Sen. Alan Simpson, R-Wyo., said further delay would only give Lucas' opponents ''enough time to get out and gin it up.''

Civil rights groups and other organizations that oppose Lucas ''are waiting to do a number and all they need is time,'' Simpson said. ''I can just see these self-annointed ones with their phone banks going goofy in the next five weeks.''

The delay came a day after Lucas received support from Sen. Arlen Specter, R-Pa., the only GOP senator whose support for the nomination was in doubt. Specter, dismissing opponents' arguments that Lucas lacked the legal qualifications for the job, said:

''It's more important to have someone who understands Supreme Court decisions from personal experience, knows it so to speak in his gut, as opposed to someone who knows where to put all the commas and semicolons.''

Sen. Dennis DeConcini, D-Ariz., is leaning toward voting in favor of Lucas but his position is not final. Heflin, who has not taken a position, had been considered the biggest question mark among committee members.

If Heflin joined DeConcini and the six Republicans in supporting Lucas, the nomination would go to the Senate with a favorable recommendation.

However, the nomination could still go to the full Senate without any recommendation from the panel, or an unfavorable recommendation if Heflin votes against confirmation.

Lucas, 61, a lifelong Democrat who joined the GOP in 1985, was sheriff and later chief executive of Wayne County, which includes Detroit. He ran unsuccessfully for Michigan governor as a Republican in 1986.

Outside the committee room, Heflin refused to disclose the nature of the new information, saying ''the allegations are not substantiated.''

''It's just something that ought to be explored,'' he added. ''It may not be worth a line in print on page 56. I don't know whether it's serious or not.''

Heflin expressed concern about a number of items on Lucas' record, saying he discussed ''a couple of them'' with President Bush during a telephone call today in which the president solicited his vote for Lucas.

''I told him I would give his request deep consideration,'' Heflin said.

Heflin also said he wanted to review ''a great number of different instances'' on Lucas' record before making up his mind.

These included a contempt-of-court citation against Lucas for failure to improve jail conditions when he was sheriff and a $594 fine he paid to the U.S. Customs Service for failing to fully report $8,884 worth of merchandise he and his his family bought during a trip to the Far East, Heflin said.

''This customs matter is a serious matter,'' Heflin said. The senator said it appeared that information about the customs incident ''was not available to the president at the time he made the nomination.''

David Runkel, spokesman for Attorney General Dick Thornburgh, said, ''We remain confident that Mr. Lucas will be confirmed by the Senate.''

''If Senator Heflin needs more time... we will be cooperative with the senator,'' Runkel said, adding that the department and Lucas will respond to any questions that Heflin wants to raise.