Beaverton, Oregon Mayor Denny Doyle on Thursday became the 300th mayor to pledge support for the legalization of gay marriage.

Doyle, now in his second term, signed on to the group Mayors for the Freedom to Marry, which launched last year with 80 mayors.

“Beaverton is a diverse, welcoming community that respects and supports marriage equality,” said Doyle. “What a wonderful valentine to send from Beaverton!”

The announcement comes on the same day supporters in Oregon began collecting signatures for a 2014 ballot initiative seeking to overturn the state's constitutional amendment limiting marriage to heterosexual unions.

(Related: Oregon gay marriage supporters want 2014 referendum.)

Evan Wolfson, founder and president of Freedom to Marry, called the group's growth “inspiring.”

“It is truly inspiring to see Mayors for the Freedom to Marry to grow as so many of our cities' leaders come together to make the case for marriage as good for the families, businesses and communities they know and serve. Mayors are in a unique position to make the case for marriage, and are accessible and responsive to the constituents and communities they serve, making them super-strong advocates for ending marriage discrimination and helping state and federal lawmakers and judges do the right thing. Freedom to Marry is proud of the way in which the mayors' leadership has encouraged people across the country to take action to help enlist their own mayors in the cause.”