MONTGOMERY, Alabama - Alabama appeared set within hours to become the 37th state where gays can legally wed, prompting one couple to pitch a tent outside a courthouse even as the state's chief justice made a last-minute bid to keep the weddings on hold Monday.

State Chief Justice Roy Moore sent a letter Sunday evening to probate judges ordering them to refuse to issue same-sex marriage licenses when the courts opened Monday morning. Moore wrote that the judges were not bound by a federal judge's ruling Jan. 23 that the marriage ban was unconstitutional.

"Effective immediately, no probate judge of the state of Alabama nor any agent or employee of any Alabama probate judge shall issue or recognize a marriage license that is inconsistent with (the Alabama Constitution)," Moore wrote.

Susan Watson, executive director The American Civil Liberties Union of Alabama, called the move by the conservative chief justice "grandstanding" and predicted licenses would be issued shortly.

"I don't think the probate judges in Alabama are going to defy a federal court judge's order," Watson said late Sunday.

US District Judge Callie Granade had ruled that the state marriage ban was unconstitutional and - in a later clarifying order - said that probate judges have a legal duty under the US Constitution to issue the licenses.

The developments unfolded as at least one couple showed up early at the county courthouse in one major city, Montgomery, and more were expected at courthouses around the state in coming hours.

Tori Sisson and Shante Wolf pitched a blue and white tent outside the Montgomery County Courthouse and hugged as they waited in hopes of being the first couple to get a marriage license in Alabama.

"It's about time," Wolfe, 21, said of gay marriage being allowed in the Deep South state.

The chief justice, Moore, has been one of the state's most outspoken critics of gay marriage. He called homosexuality an "evil" in a 2002 custody ruling and urged judges to reject issuing such licenses in recent days.

A few probate judges have said they would refuse to issue the licenses until they received greater clarity from the courts. Moore, as head of the court system, upped the ante Sunday night by sending the directive, although, it was unclear what enforcement provision he has.

Moore's letter to the probate judges said Alabama Gov. Robert Bentley can take action against elected officials who fail to follow the law.

Jennifer Ardis, a spokeswoman for Bentley, said she did not know about Moore's letter and did not have an immediate comment Sunday evening.

Couples plan to seek marriage licenses across the state with marriage equality groups providing ministers and judges to perform ceremonies in Huntsville and Birmingham.

Attorney General Luther Strange has asked the US Supreme Court to put aside Granade's order since justices are expected to issue a ruling later this year on whether gay couples have a right to marry nationwide. The high court had not ruled on the state's request within hours of the opening of courthouses Monday.

The ACLU has established a hotline for couples to report if they are refused a license. Watson said the ACLU will be at courthouses across the state, not just to be prepared for problems, but to hand out balloons and gifts to joyful couples.