The national debate over same-sex unions lands squarely in Maryland this month, as legislators and lobbyists mobilize for a series of noisy battles over how gay couples will be treated in the eyes of state law.

Lawmakers on both sides of the issue are preparing legislation that would add same-sex unions to the roster of contentious matters facing the 2005 General Assembly session.

With a Sun poll showing Marylanders divided, but leaning against civil unions for same-sex couples, gay-rights activists and opponents are organizing supporters for a political show of force Jan. 27 in Annapolis.

"I think it's clear that this year, Maryland's in play," said Tres Kerns, a leading opponent of same-sex marriage and co-founder of Take Back Maryland.

The gay marriage issue is not new here. The state has a 32-year-old law defining marriage as a union between a man and woman, and from time to time the General Assembly has considered additional restrictions on same-sex couples.

But in recent years, gay-marriage opponents have viewed Maryland as too liberal on social issues to make more restrictions politically feasible.

But emboldened by the success of anti-gay marriage referendums in 11 states in November, opponents of same-sex unions expect to push for a state constitutional amendment banning gay marriage - or at least a restatement of current law making it clear to the courts that the legislature is against the idea.

"National momentum can only go so far," said Carrie Gordon Earll, a spokeswoman for Focus on the Family, a conservative lobbying group. "Ultimately it comes down to the people on the ground, in their counties, putting pressure on their legislators."

On the 10 Christian radio stations in the state where the group airs its broadcasts, it is urging listeners to join the Jan. 27 rally.

Organizers predict the "marriage protection" gathering will attract tens of thousands of supporters to put pressure on the legislative committees that bottled up a similar measure last year.

For that grass-roots strategy to work, the public response would have to be overwhelming. Even the most ardent supporters of a constitutional amendment acknowledge that the legislature is not amenable to the idea.

Del. Joseph F. Vallario Jr., the Prince George's County Democrat who leads the House Judiciary Committee, said he was unlikely to support an amendment for both logistical and political reasons - even though he personally opposes gay marriage.

First, he pointed out, amendments are usually considered only in election years. Second, he said, Maryland law adequately defines marriage as a union between a man and woman, so there is no need for a redundant amendment. He said he would consider an amendment only if the law appeared to be in jeopardy from the courts.

Nor is he likely to be swayed by demonstrations. "No. I won't do it just because a lot of people want it. That's not the way we work," he said.

Still, Vallario said he expects to hold a hearing on the amendment and bring it to a vote in committee.

Road to ratification

Even if it did emerge, a constitutional amendment would require a three-fifths' majority in each chamber to pass. Then it would have to be approved by voters next year - the ultimate goal for the amendment's supporters.

"People in the state ought to be able to decide for themselves," said Del. Charles R. Boutin, a Republican representing Harford and Cecil counties who plans to sponsor the amendment again this year.

Although it's the most extreme, Boutin's measure is one of at least three proposed restrictions on same-sex unions being drawn up. Another would bar gay couples from adopting children, while a third would reiterate the 1973 law defining marriage and ensure that Maryland will not recognize gay marriages legalized out of state.