The D.C. Council passed the measure in May. It's currently under congressional review.
The elections board on Wednesday heard four hours of testimony regarding a proposed referendum on the issue. A coalition of black ministers who oppose the bill and want the referendum say the bill is the first step toward legalizing gay marriage in Washington. They want a public debate on the matter.
Council member Phil Mendelson, who sponsored the bill, says the city would be treating gay and straight couples differently if it only recognized some out-of-state marriages.
The board is expected to make a decision by at the end of this week or early next week.