Same-sex marriage supporters, including Maryland Gov. Martin O’Malley, squared off Tuesday in a lengthy legislative hearing against ministers and others who urged that the state not abandon its tradition of limiting nuptials to one man and one woman.

O’Malley (D), who has vowed to pass legislation along the lines of a bill that fell short last year, said the issue is about “human dignity” and asked state senators to view it through the eyes of children.

“It’s not right, and it is not just that the children of gay couples should have lesser protections than the other children of our state,” O’Malley told the Senate Judicial Proceedings Committee, the first panel to consider his legislation this year.

During a packed hearing that stretched more than four hours, opponents argued that the legislation is an affront to their religious sensibilities and that reworked “religious exemptions” included in O’Malley’s bill are still insufficient to protect their rights.

“This is a fight we will not run from,” said Robert J. Borger, pastor of Annapolis Evangelical Presbyterian Church, saying that gay unions are “not rooted in natural law.”

The Senate narrowly passed a similar bill last year that O’Malley did not sponsor, and the chamber is widely expected to approve this year’s bill. The drama during the 90-day session will come in the House of Delegates, where last year’s bill failed and no lawmakers have announced a change in position.

A Washington Post poll published this week found that half of Marylanders now favor the legalization of same-sex marriage, although support varies considerably along the sensitive lines of race, religion and age.

O’Malley was joined in his advocacy Tuesday by several other leading Maryland politicians. Attorney General Douglas F. Gansler (D) called passage of the bill “a moral imperative.” Baltimore Mayor Stephanie Rawlings-Blake (D) said it was “long overdue.”

Sen. Richard S. Madaleno Jr. (D-Montgomery) spoke in personal terms, telling colleagues “I don’t know why people fall in love” but that he and his male partner are now a family that includes children.

Sen. Allan H. Kittleman, the only Republican legislator to support last year’s bill, also testified, asking that his colleagues set aside concerns of potential negative consequences suggested by opponents.

“You don’t take away someone’s civil rights because of what might happen,” said Kittleman (R-Howard).

Bill supporters included several religious leaders, but clergy members played a greater role in making the case against the legislation.

The Rev. Joel R. Peebles, pastor of Jericho City of Praise in Landover, testified with his wife of 18 years standing beside him and told senators that they have four children.

“None of us, not one of us, would be here if not for a relationship between a man and a woman,” Peebles said.

Derek McCoy, president of Maryland Family Alliance, a group lobbying against the bill, echoed that point and asked senators to “hear the voices of the people.” He was referring in part to a rally Monday night that drew a few hundred bill opponents to Annapolis.

Mary Ellen Russell, executive director of the Maryland Catholic Conference, was among those who argued Tuesday that unions of same-sex couples are not traditional marriages.

“We can’t equate things that are not the same,” Russell said.

If the goal is to provide equal protections under the law, she asked senators, then why not approve civil unions as an alternative to same-sex marriage?

Russell later acknowledged that it was unclear whether her organization would support legalization of civil unions, either, noting that the Catholic Church has opposed them in other states.

Several speakers questioned whether legal protections included in O’Malley’s bill are sufficient to protect religious groups that do not believe in gay unions.

The bill makes clear that religious leaders are not required to officiate at same-sex marriages if that conflicts with their doctrine.

Brian W. Raum, senior counsel at the Arizona-based Alliance Defense Fund, argued that protections should be extended to businesses, such as wedding planners, who do not believe in gay nuptials.

In arguing against Raum and others, Sen. Jamie B. Raskin (D-Montgomery) said that lawmakers should not turn back the clock on existing anti-discrimination measures in Maryland law.

Under current law, Raskin noted, businesses that provide “public accommodations” cannot discriminate based on the sexual orientation of a customer.

“We’ve already driven over that bridge,” Raskin said.

Separately Tuesday, during an appearance at a prayer breakfast with supportive clergy, House Speaker Michael E. Busch said the push for legalizing same-sex marriage is “clearly an issue of civil rights.”

Busch (D-Anne Arundel) came to support that position during last year’s debate on the issue, but the prayer breakfast in Annapolis marked the first time he had spoken out as forcefully in such a setting.

A number of Busch’s colleagues who support the bill have privately said they would like to see more vocal support on his part.