PECOS, Texas — Four Texas cities that filed a federal lawsuit challenging the constitutionality of the Texas Open Meetings Act must withdraw from the case because, as government agencies, their First Amendment rights cannot be violated, the state’s attorney general said yesterday.

Alpine, Pflugerville, Rockport and Wichita Falls and 15 elected state officials filed a lawsuit in December arguing that the act violates the First Amendment by barring elected officials from speaking in public or private about public issues.

The act bars a quorum of members of a government body from deciding issues in secret. Violations are punishable by up to six months in jail and a $500 fine.

The plaintiffs argued that some communication, including in e-mails and messages sent using social-media Web sites, should be allowed by a quorum outside of a posted meeting.

Yesterday, Texas Attorney General Greg Abbott filed a 10-page motion in the federal court in Pecos to dismiss Alpine, Pflugerville, Rockport and Wichita Falls from the case. He said only citizens have First Amendment rights and that the cities therefore could not argue that their rights had been violated.

The cities are “creatures of the state” that “may not assert constitutional claims against the state,” he said in the filing.

Rod Ponton, a lawyer for the plaintiffs, said cities, along with churches, labor unions and other organizations, represent the interests of citizens and elected officials.

“Cities have the right to represent the interests of their mayors and city council members and they also have the right to represent the interests of citizens of the city who vote those people into office,” Ponton said. “The attorney general shouldn’t try to dodge the core issue, which is that public officials have the same First Amendment rights as everyone else.”

It was not clear when Abbott’s motion would be ruled on.