DENVER - Same-sex marriages resumed in some Colorado counties on Monday, after the US Supreme Court declined to hear an appeal of a ruling against Utah's marriage law.

That allows the Utah ruling from the federal 10th circuit court of appeals in Denver to stand, a move that Colorado Attorney General John Suthers (R) says invalidates his state's voter-enacted law against same-sex marriage.

"Once the formalities are resolved, clerks across the state must begin issuing marriage licenses to all same-sex couples," Suthers wrote in a statement released Monday morning. "We will file motions to expedite the lifting of the stays in the federal and state courts and will advise the clerks when to issue licenses."

FULL STATEMENT: Colorado AG Suthers: Issue same-sex marriage licenses

Pueblo and Larimer counties have both started issuing same-sex marriage licenses after the ruling.

Immediately following the announcement from the high court, multiple county clerks in Colorado told 9NEWS they were working to confirm with their attorneys that marriages for same-sex couples could be legally performed.

Hundreds of same-sex marriage licenses were issued in Colorado for a series of weeks earlier this year by clerks in Boulder, Denver, and Pueblo counties, which based their actions on the initial 10th circuit decision.

Adding a wrinkle to the story, Boulder, Denver and Adams counties are currently under stays from the Colorado state supreme court which forbids them from issuing marriage licenses to same-sex couples.

RELATED STORY: Pueblo Co. to start issuing gay marriage licenses now

Denver County Clerk Deb Johnson told 9NEWS she is waiting on a legal resolution in the state's high court before her office may resume issuing licenses.

An attorney for same-sex couples in the state-level case says resolving this issue is a top priority that he expects to be resolved quickly.

"The stay should be dissolved very quickly by the Tenth Circuit and same sex marriage should be legal in Colorado within days," said attorney David Lane in a written statement.

Suthers eventually stopped the licenses from being issued by threatening legal action, insisting that the matter would not be properly resolved until the US Supreme Court weighed in.

The nation's high court did that on Monday by announcing it had declined to hear the Utah case and a series of others, a move that effectively upheld the appellate court rulings against bans on same-sex marriage.

9NEWS will continue to update this developing story as more details become available.

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