(CNN) -

Utah will become the first state to ask the Supreme Court to uphold its ban on same-sex marriage, the latest legal step in what could become a constitutional showdown.

The state's attorney general, Sean Reyes, announced Wednesday the justices would be asked "in coming weeks" for final review after an appeals court struck down the prohibition last month.

There's no guarantee the court will take it up, however. The Supreme Court could agree to review the ban or wait for lower courts to decide other cases first. The earliest time frame for a decision is late September.

Reyes office said in a statement that he "has a sworn duty to defend the laws of our state."

Enforcement of the Utah appeals court decision was stayed, meaning same-sex couples there cannot get married for the time being.

Federal and state judges in more than a dozen states have struck down same-sex marriage bans in the past eight months. It is fully legal in the District of Columbia and 19 states.

Last year, the Supreme Court issued two 5-4 rulings on same-sex marriage.

The majority struck down a federal law known as the Defense of Marriage Act, which had denied legally married same-sex couples the same federal benefits, including tax breaks, available to heterosexual couples.

The court also dismissed an appeal in a California case that cleared the way for same-sex marriages to resume there.

Those decisions launched round two of the debate, now playing out in courts nationwide over broader constitutional questions.

Evan Wolfson, president of Freedom to Marry, a group campaigning for same-sex marriage nationwide, said the Supreme Court should take up the Utah appeal and "swiftly move to end marriage discrimination."