O'Malley, a Democrat who has long advocated an end to capital punishment, asked senators to consider both "empirical evidence" and "higher truths" when making their decision. "This goes to the very soul of who we are as a people and as a state," he said.
The governor's testimony before a closely divided Senate committee that has twice rejected repeal efforts came just hours after Sen. President Thomas V. Mike Miller sternly warned his colleagues not to let the emotionally charged issue hold up other legislative business.
After 4 1/2 hours of testimony from more than 50 witnesses - including political heavyweights, law enforcement officials and relatives of murder victims - the Senate Judicial Proceedings Committee will decide next whether to vote or to take a more unusual route by sending the repeal to the full Senate without a recommendation.
The committee appears poised to take that contentious step, which would need approval from six of its 11 members.
Yesterday, Sen. James Brochin, a Baltimore County Democrat who opposes a total repeal, said he was "strongly considering" joining repeal proponents in turning the death penalty debate over to the full chamber. Another repeal opponent, Sen. Alex X. Mooney, a Republican representing Frederick and Washington counties, also has said he would like the entire Senate to weigh in.
Acknowledging the likelihood of a full-body debate, Miller, a supporter of capital punishment, said he worried that the discussion could last for days and "turn ugly," similar to a filibuster on abortion rights in 1990. There might not be enough senators on either side to block a filibuster, and a narrow majority of senators would likely vote down a repeal.
A recent survey of all 47 senators by The Baltimore Sun found that 19 are inclined to vote for O'Malley's bill and 24 oppose a total repeal of the death penalty. Four declined to answer as to how they would vote. Twenty-nine votes are needed to end a filibuster.
"These are fiery emotions," Miller said from the Senate floor yesterday, encouraging the Judicial Proceedings members to vote with him to limit debate if they forward the repeal without a recommendation.
The committee probably will wait a week before making its next move, said Sen. Lisa A. Gladden, the vice chairman and a Baltimore Democrat. She sponsored the repeal measure backed by O'Malley.
Yesterday's hearing opened with an impassioned plea by the governor, who said the country was "not founded on fear and retribution" or the belief that two wrongs make a right. He referred frequently to the work of a commission he appointed last summer to study capital punishment in Maryland.
That commission, headed by former U.S. Attorney General Benjamin R. Civiletti, concluded that the death penalty is costly, ineffective and unevenly applied. Civiletti also testified yesterday, fielding the most questions of any speaker.
Sen. Nancy Jacobs, a Republican representing Harford and Cecil counties, asked Civiletti why he believes that "regional disparities" in the application of the death penalty are troublesome. Baltimore County seeks the death penalty far more often than other parts of Maryland. Other places, such as Baltimore City, almost never file capital charges.
"I do not believe that the irreversible punishment of death should be frivolously or capriciously applied based on where the occurrence happened," Civiletti replied. "I think there ought to be a reasonable uniformity. It is a statewide law."
Former Gov. Marvin Mandel testified first for the death penalty proponents. He said he had once opposed capital punishment but several experiences changed his mind. He said he believes capital punishment is an effective deterrent to crime.
Former Gov. Harry R. Hughes wasn't at the hearing but wrote to O'Malley, in a note distributed by O'Malley aides: "It seems to me a civilized society should be above that for both moral and practical reasons."
Baltimore County's top prosecutor, Scott D. Shellenberger, a member of the Civiletti commission, urged the lawmakers to keep the death penalty. "Maryland is different," he said. "We're much more careful here about who we put on death row. We're much more judicious."
Since the Maryland General Assembly reinstated capital punishment in 1978, five men have been executed. Five remain on death row.
There have been no executions since December 2006, when Maryland's highest court ruled that lethal injection regulations had not been properly adopted. The Department of Public Safety and Correctional Services is revising protocols.
Union leaders for police officers and state troopers also testified against a repeal, saying that it would put officers at risk.
"We get to see firsthand what one human being did to another," said Bernard Shaw of the Maryland Troopers Association.
Baltimore Sun reporter Laura Smitherman contributed to this article.