The influential head of a U.S. gay rights group urged Japan Thursday to help legalize same-sex marriage by building favorable public opinion.

In a speech at an Osaka ward office, Evan Wolfson, founder and president of Freedom to Marry, said lobbying, campaigns and support movements led to the U.S. Supreme Court ruling in 2015 that recognized a constitutional right to same-sex marriage nationwide.

Wolfson has been listed as one of Time magazine's 100 most influential people in the world and is widely considered the architect of the movement that led to the landmark ruling.

About 30 people gathered at the event co-hosted by the U.S. Consulate General Osaka-Kobe and Yodogawa Ward, which officially declared support for the lesbian, gay, bisexual and transgender community in 2013.

The ward has since been exchanging views with the LGBT community, providing phone consultations and holding educational projects to support sexual minorities.

Japan has not legalized same-sex marriage, but some municipalities, including Tokyo's Shibuya and Setagaya wards, have taken steps to back gay unions, issuing certificates to same-sex couples to enable them to have access to services they had previously been denied.