A federal judge Thursday rejected a last-minute bid by conservative groups to block the nation's first state-sanctioned gay marriages (search) from taking place in Massachusetts on Monday.

U.S. District Judge Joseph Tauro (search) said the state's high court acted within its authority in interpreting the Massachusetts Constitution (search).

The plaintiffs immediately announced they would take their case to the 1st U.S. Circuit Court of Appeals — and to the 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 sprearheaded 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 ruling "would be to deprive that court of its authority and obligation to consider and resolve, with finality, Massachusetts constitutional issues," Tauro wrote.

That court "has the authority to interpret, and reinterpret, if necessary, the term marriage as it appears in the Massachusetts Constitution," Tauro wrote.

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 urged the federal judge to "prevent this constitutional train wreck."

A state attorney arguing on behalf of the Supreme Judicial Court said the court based its 4-3 decision on the Massachusetts Constitution and that the case did not belong in federal court.

"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."

Staver expressed optimism that the federal appeals court, and the Supreme Court if necessary, would hear his case before Monday.

A confusing patchwork of local rules has developed for gay marriages in the state.

Boston's chief lawyer, Merita Hopkins, announced Wednesday the city will accept marriage applications starting Monday "from everyone except partners who do not reside in Massachusetts, and neither one of which intends to reside in Massachusetts."

However, officials said the city would not demand proof of residency. Instead, couples would be required to fill out a form saying they plan to move to Massachusetts, and sign the form under penalty of perjury.

The move apparently falls in line with Gov. Mitt Romney's efforts to limit same-sex unions by making them illegal for non-residents, although communities across the state are divided.

Officials in Worcester, the state's second-largest city; the Cape Cod town of Provincetown; and the Boston suburb of Somerville have said they will issue licenses to out-of-state couples.

But officials in Cambridge and Northampton, a western Massachusetts city with a large gay population, said they would adhere to Romney's guidelines.

Elsewhere Thursday, a Christian legal group sued the mayor and city council of San Jose, Calif., over their decision to recognize the same-sex marriages of gay municipal employees who wed elsewhere.

The Alliance Defense Fund said the city council's March vote, designed to provide expanded health and retirement benefits to the partners and children of gay city workers, violated a California law holding that only marriages between a man and a woman are valid.