MALDEN -- House Speaker Salvatore F. DiMasi predicted yesterday that next month the Legislature will reject a proposed constitutional amendment to ban same-sex marriage and allow civil unions, the strongest signal yet that the compromise given preliminary approval by lawmakers last year is headed for defeat.
''Everybody anticipates that there won't be enough votes to pass this," DiMasi, a supporter of same-sex marriage, said in an interview. ''That seems to be pretty clear."
The compromise amendment, sponsored by Senate President Robert E. Travaglini and Senate minority leader Brian P. Lees, has lost support since its narrow passage in March 2004. Legislative elections last fall added more gay-marriage supporters to Beacon Hill, and some conservative lawmakers have abandoned the amendment in favor of a separate ballot measure aimed for 2008 that would outlaw gay marriage but not allow civil unions.
The House speaker's remarks reflect a growing consensus that the amendment will not have the votes to pass when the Legislature meets in a Constitutional Convention Sept. 14. The amendment must clear the Legislature to be placed on the 2006 ballot.
''I don't see the Travaglini amendment moving forward," agreed Representative Thomas M. Petrolati, the speaker pro tem of the House, who voted for the amendment last year and plans to do so again.
Still, a big question mark remains because of upcoming developments that involve same-sex marriage.
By Sept. 7, a week before the Legislature convenes, Attorney General Thomas F. Reilly must decide whether to certify the separate 2008 measure or reject it. If Reilly agrees with gay-rights supporters that the 2008 initiative is unconstitutional, some lawmakers who oppose same-sex marriage might change course and back the Travaglini-Lees measure when the Legislature convenes.
One of those opponents, Representative Philip Travis, Democrat of Rehoboth, declared the 2006 amendment defeated at the unveiling of the 2008 initiative two months ago. Travis said yesterday, however, that if Reilly does not certify the 2008 petition, he will have no choice but to back the compromise that's before the Legislature.
''[It] will have to be supported, because there will be nothing to protect marriage," he said.
Kris Mineau -- president of the Massachusetts Family Institute, a group opposed to gay marriage and civil unions -- said he is confident his allies have enough votes to soundly defeat the Travaglini-Lees amendment. He said his organization is in a ''full-court press" to make sure that happens.
But asked by a reporter if his organization will urge lawmakers to back the 2006 amendment if Reilly does not certify their 2008 initiative, he would not rule it out, saying, ''We'll have to reassess the situation if it comes to that."
Thus Reilly's rejection of the 2008 measure would be bittersweet for gay-rights groups: They don't want the 2008 ballot question to succeed, nor do they want to see a bloc of conservative legislators throw their support behind the 2006 amendment.
It's one reason why Lee Swislow, executive director of Gay & Lesbian Advocates & Defenders, isn't convinced that her side will prevail on Sept. 14.
''I would love to be optimistic," she said. ''But until it's voted down, I, as will GLAD and I think all the organizations involved, will continue to do everything we can to defeat it."
''We are fully aware that the votes of somebody like Phil Travis could be affected by Reilly's decision," added Arline Isaacson, cochairwoman of the Massachusetts Gay & Lesbian Political Caucus.
The compromise amendment to ban gay marriage and create civil unions passed 105-92 in 2004; it needs 101 votes to win approval this round and be put to voters next year.
Several legislators who voted for the Travaglini-Lees measure in 2004 have said publicly that they are rethinking their support, including Representative Anthony Petruccelli, an East Boston Democrat and Travaglini ally who was quoted by the newspaper Bay Windows last week as saying that he will not vote for the amendment next month. DiMasi said yesterday that he anticipates a few other former supporters will change their votes, too.
Advocates for gay rights were disappointed that the Legislature picked Sept. 14 for the debate on same-sex marriage. They fear they won't have enough time to generate sufficient opposition. But DiMasi said that although he had hoped Travaglini would pick a date later in the fall, there is not necessarily a benefit to waiting, if the votes are there now.
''I always say, when the votes are there, you take them," DiMasi said, pointing out that many lawmakers are eager to get the gay-marriage vote out of the way and move on to healthcare, economic development, and other matters.
Travaglini spokeswoman Ann C. Dufresne said yesterday that the Senate president remains committed to his amendment and that debate on gay marriage will definitely take place Sept. 14.
''His support has not changed," she said.
Travaglini has not yet polled or talked to legislators to discern how the vote will go, Dufresne said.
But many legislators believe there's a good chance it will fail.
''I think there's a sense that the amendment won't have the support it had last year," said Senator Susan C. Fargo, a Lincoln Democrat who voted against it in 2004. ''I think people have changed their minds, now that we've had gay marriages for more than a year."
DiMasi also criticized the 2008 ballot measure yesterday, calling it offensive and onerous.
''And I think most people would look at it that way," said DiMasi, who made his comments to reporters after speaking on economic development to the Malden Chamber of Commerce.
Scott Helman can be reached at email@example.com