Brian Brown, president of the National Organization for Marriage (NOM) and the World Congress of Families (WCF), is heading to Mexico to lend his support to a campaign against a proposal to legalize marriage rights for gay and lesbian couples throughout the country.

Mexican President Enrique Pena Nieto in May asked lawmakers to debate the issue. While Mexico's highest court has ruled that gay couples have a constitutional right to marry, most states continue to deny marriage licenses to gay couples.

The Roman Catholic group National Front for the Family last weekend organized marches against the proposal in multiple cities. The activists are calling for a constitutional amendment which would exclude same-sex couples from marriage. A national march in Mexico City is scheduled for September 24.

(Related: Boy confronts thousands of protesters marching against gay marriage in Mexico.)

Brown on Wednesday called on World Congress of Families supporters to add their names to a petition which he said he would deliver personally to the leaders of the National Front for the Family during an upcoming visit to Mexico City.

“Even though most people can't be there in person, you can lend your name and voice to the effort to uphold marriage, protect children from 'gender ideology' and support the right of parents to direct their children's education according to their own values and principles,” Brown wrote in an email to supporters.

“The National March for the Family has the potential of being the largest single demonstration of support for marriage, children and parental rights in history. Beyond its significance in the domestic affairs of Mexico, this march also can help advance the worldwide movement to support marriage, religious liberty and the truth of gender that we were made male and female,” he added.