The Washington suburb of College Park, Md., whose city leaders thought Tuesday they had approved a measure to allow noncitizens to vote in city elections, said that in fact the change did not gain the required votes for approval and was not adopted.

“It is with considerable embarrassment and regret that we acknowledge our oversight,” Mayor Patrick Wojahn and City Council members said Saturday.

The measure, it turns out, needed more “yes” votes than it got.

The initial council action came by a 4-to-3 vote after a heated and emotional debate over illegal immigration, and it appeared to make the home of about 32,000 residents and the University of Maryland’s flagship campus the largest U.S. city to allow noncitizens to cast ballots in municipal elections.

But in a three-paragraph statement late Friday, the city said that while most council actions require a simple majority of members present to pass, charter amendments such as the voting measure require a supermajority of six votes from the nine-member council.

The change requiring a supermajority of the votes that include the mayor and eight district representatives took effect in June. The noncitizen-voting charter change proposal was introduced June 13.

“Therefore, Charter Amendment 17-CR-02 was not adopted,” the city statement said.

Unlike most other states, Maryland allows towns and cities to decide who can vote in local elections. In recent years, Hyattsville, Mount Rainier, Takoma Park and several smaller towns have extended that privilege to noncitizens.

On Saturday, College Park’s mayor and council apologized to residents.

“We each accept our responsibility for not realizing the impact of the June charter amendment on Council procedures and we apologize to our residents,” the mayor and council said in the statement. They added their appreciation of the engagement and time invested by residents, concluding, “We acknowledge that all residents are an important part of the College Park community and we will continue to seek ways to make everyone feel welcome and included in our City.”

On Tuesday, Wojahn cast the deciding vote killing motions that would have let city residents weigh in on the decision either by referendum or advisory committee, which would have limited the expansion of the vote.only to legal permanent U.S. residents, or green-card holders.

Despite the passion on both sides, the effect of expanding voting rights to noncitizens has been minimal. In Hyattsville, 33 city-only voters registered for local elections in May — the first since its amendment passed in December — and 12 actually voted, according to a letter signed by several advocacy groups. In Mount Rainier, 20 noncitizens registered to vote.

The College Park proposal to allow undocumented immigrants, student visa holders and residents with green cards to vote starting in 2019 came eight months into a crackdown on illegal immigration by President Trump and one week after his administration said it would wind down a deportation-relief program for immigrants illegally brought to the United States as children.

About 20 percent of the city’s 32,275 residents are ­foreign-born, according to data from the Census Bureau. The U-Md. campus, with more than 27,000 undergraduates, has about 3,600 international students.