BOSTON (AP) – A federal judge Thursday rejected a last-minute bid by conservative groups to block the nation’s first state-sanctioned gay marriages from taking place in Massachusetts next week.

U.S. District Judge Joseph Tauro said Massachusetts’ high court acted within its authority in interpreting the Massachusetts Constitution.

The plaintiffs immediately announced they would take their case to the 1st U.S. Circuit Court of Appeals, and to the U.S. Supreme Court if necessary. The 1st Circuit agreed to review the case on an expedited basis.

“The 1st Circuit is reviewing it and is aware of the deadline,” Gary Wente, the circuit executive for the appeals court, said late Thursday.

Tauro heard arguments Wednesday on a petition spearheaded by the Florida-based Liberty Counsel and joined by the Catholic Action League, 11 state lawmakers and conservative legal groups in Boston, Michigan and Mississippi.

Granting a stay of the Supreme Judicial Court’s landmark ruling “would be to deprive that court of its authority and obligation to consider and resolve, with finality, Massachusetts constitutional issues,” Tauro wrote.

“The SJC has the authority to interpret, and reinterpret, if necessary, the term marriage as it appears in the Massachusetts Constitution,” Tauro wrote. “There can be no question that the meaning of the term marriage is an issue that arises under the Constitution.”

Mathew Staver, president and general counsel of the Liberty Counsel, had argued that the state’s high court overstepped its bounds when it ruled in November that gay marriage should be legal in Massachusetts. He said only the Legislature should define marriage and pleaded with the federal judge to “prevent this constitutional train wreck.”

A state attorney arguing on behalf of the SJC said that the court based its ruling on the Massachusetts Constitution and that the case did not belong in federal court.

The Massachusetts court, in a 4-3 decision, ruled the state could not prevent same-sex couples from marrying. City and town clerks are expected to begin issuing marriage licenses to gay couples beginning on Monday.

“If that goes into effect it will cause social unrest and the explosion of litigation throughout the United States,” Staver said Thursday after the ruling was released. “This shows how four individuals can affect the entire country.”

Despite Tauro’s ruling, Staver said he’s optimistic the federal appeals court, and the Supreme Court if necessary, would hear his case under an emergency appeal before Monday.

AP-ES-05-13-04 1746EDT