The Constitution would instead be silent on the issue, leaving open the possibility of a future legalization without specifically promoting it.

The commission is headed by Raúl Castro, the Communist Party’s head and former president.

His daughter, Mariela Castro, is a lawmaker known as Cuba’s highest-profile advocate for lesbian, gay, bisexual and transsexual rights. Her advocacy has helped rehabilitate the image of L.G.B.T. rights in Cuba, where the Castro-led government sent gay men to work camps in the 1960s, and where widespread persecution continued through the 1970s.

While Havana and some other Cuban cities have flourishing gay communities, anti-homosexual attitudes remain deeply rooted among much of the population. Cubans who ordinarily shy from open criticism of the government spoke out in large numbers against the proposed language promoting gay marriage during public consultations on the draft.

Cuba’s rapidly growing evangelical churches also staked out positions against the article, increasing pressure on a government unused to public criticism.

The new charter is expected to be offered for approval at a public referendum in early 2019.

The dropping of the gay marriage language is the third dramatic reversal this month for a government that for decades has issued most laws and regulations with little open debate or insight into the working of the ruling Communist Party.