A sharply divided Maryland Senate agreed yesterday to debate a temporary halt to executions in the state, but proponents acknowledged that they don't have the votes to pass a capital punishment moratorium, much less override a promised veto by Gov. Robert L. Ehrlich Jr. (R).

The Senate voted 24 to 23 to allow the bill to come to the floor, with Senate President Thomas V. Mike Miller Jr. (D) casting the decisive vote.

Such preliminary votes often reflect the final outcome on a measure, but in this case a number of senators said they voted yes as a courtesy to the Legislative Black Caucus, which has made the bill a top priority, and other backers. Miller, who supports the death penalty, said he plans to vote no when the chamber takes up the bill on final passage next week, and sponsors say at least two other senators will also change sides.

"The handwriting is probably on the wall unless we can change some minds," said Sen. Ralph M. Hughes (D-Baltimore), one of the measure's principal sponsors.

Hughes and others plan to spend the weekend lobbying their colleagues. "Everyone's known all along that this was going to be close," said Sen. Brian E. Frosh (D-Montgomery). "But I'm not ready to give up."

Still, even if they won approval in the Senate, supporters say they would not be able to muster the three-fifths majority -- 29 votes -- needed to override a veto. Frosh said the governor would need to change his mind if the bill was going to become law.

Upon taking office in January, Ehrlich effectively lifted a death penalty moratorium imposed by his Democratic predecessor, Parris N. Glendening, and a spokeswoman said yesterday that the governor has had no change of heart.

"The vote shows that the legislature is split down the middle on this issue," Shareese DeLeaver said. "The governor feels the death penalty is appropriate for the most egregious crimes. He hasn't wavered in his position, nor does he intend to."

The bill -- which is backed by Maryland Attorney General J. Joseph Curran Jr. (D); religious groups, including the Maryland Catholic Conference; and national activists who favor abolishing capital punishment -- would impose a moratorium on executions in the state until July 1, 2005.

Supporters say the halt is needed to give lawmakers time to evaluate a recent University of Maryland study that found prosecutors in Maryland are far more likely to seek the death penalty for black suspects charged with killing white victims than for anyone else. Eight of the 12 men on death row in the state are black, and all killed white victims. The study also found widespread disparities among jurisdictions, with some prosecutors pushing for the death penalty in virtually all eligible cases while others rarely, if ever, arguing to execute those responsible for capital crimes.

Maryland is one of the central battlegrounds in a death penalty debate across the nation. It was one of only two states to have a moratorium before Ehrlich took office. In the other, Illinois, the governor cleared out death row before leaving office two months ago, commuting the sentences of 167 people to life without parole and pardoning four men he said had been beaten into confessing to murders they did not commit. This week, a committee appointed by the Pennsylvania Supreme Court called on Gov. Edward G. Rendell (D) and that state's high court to order a moratorium so that racial bias in that system can be studied.

Maryland's study results suggest that the General Assembly should have time to come up with legislative fixes, moratorium proponents argued yesterday. "Justice should be blind," said Sen. Leo E. Green (D-Prince George's). "Seventeen months -- that's all we're asking for."

Others pointed to the case of Kirk Bloodsworth, who was freed from Maryland's death row by DNA evidence a decade ago, the first such exoneration in the nation.

Frosh said that without reform, he is confident that Maryland will execute an innocent person. "The question you have to ask is how much risk are you willing to accept?" he asked. "How many people are you willing to execute?"

But capital punishment supporters said the bill was a thinly veiled attempt to do away with the death penalty, and they spoke with equal passion about the "monsters" on death row who commit heinous crimes.

They, too, pointed to the Bloodsworth case, saying it shows that the system works. The advent of DNA testing and the fact that only 12 people are on death row in Maryland should give people more confidence in the process, they argued.

As for the University of Maryland study, Sen. Thomas M. Middleton (D-Charles) argued that defense lawyers can present the findings to judges considering capital cases.

"The system is as fair as it possibly can be," seconded Sen. Richard F. Colburn (R-Dorchester). "Unfortunately, there are disparities."

Senate President Thomas V. Mike Miller Jr., left -- with Sens. Nathaniel J. McFadden and Ralph M. Hughes -- cast the deciding vote to let the bill reach the floor but plans to oppose it next week.