The Maryland State House is seen reflected in a window in Annapolis. (Matt McClain/The Washington Post)

Roughly half of Maryland voters oppose a bill that is moving through the General Assembly that would allow gender-neutral driver's licenses, according to a poll released Tuesday by Gonzales Research and Media Services.

According to the findings, 51 percent of Marylander voters said they do not favor giving drivers the option to identify as “unspecified” on their licenses. The legislation approved by the Senate last month would require the state Motor Vehicle Administration to issue licenses or identification cards that show an “M” for male drivers, an “F” for female drivers and an “X” for drivers who don’t identify with a specific gender.

The legislation has been heard by a committee in the House of Delegates and is awaiting a vote there.

A smaller 37 percent of the respondents said they favor the bill, while 12 percent did not answer the poll question.

The poll, which surveyed 817 registered voters, was conducted from Feb. 22 through March 1. The margin of error is plus or minus 3.5 percentage points.

The poll findings, much like the 32-to-14 vote in the Senate last month, largely fall along partisan lines. Sixty percent of registered Democrats and 36 percent of unaffiliated voters favor gender-neutral licenses. Twelve percent of Republicans said they support the idea.

State Sen. William C. Smith (D-Montgomery), the lead sponsor of the bill, told his colleagues last month that 11 countries and five states — including California, Colorado and Maine — offer gender-neutral options on identification cards.

The District, which issued its first gender-neutral ID in 2017, is believed to have been the first U.S. jurisdiction to do so. Next year, the city will allow families to list their child as non-binary on school enrollment forms. And last month, several major airlines said they would allow passengers to identify as “unspecified” or “undisclosed” when they buy tickets.

In the Maryland Senate last month, several GOP lawmakers who opposed the bill questioned whether non-binary licenses would be “accurate.”

“Are we going to call them X men?” said Minority Leader J.B. Jennings (R-Harford). “That’s your identification. . . . When it comes to that information, I think it should be accurate.”

The remarks drew outrage from advocates. State Sen. Mary L. Washington (D-Baltimore City), the only openly gay member of the Senate and a co-sponsor of the bill, told her colleagues that requiring Marylanders with non-binary gender identities to list themselves as either male or female is akin to telling them to lie on a government document.

Scott Clement contributed to this report.