In an email titled, "Boom!" the Johnson campaign says:

The major show of grassroots force follows closely on the heels of the news that Johnson has completed the fundraising necessary to reach the legal spending limits for the race. The 577 endorsers range from PTA presidents, block association leaders and tenant association presidents to Rory O'Malley, the Tony-nominated star of “Book of Mormon” and co-founder of Broadway Impact.  They also include 20 well-known state and national leaders in the movement for LGBT rights.

“Our campaign is moving into a new phase of excitement,” Mr. Johnson said.  “The support from grassroots leaders and activists is overwhelming.  Together, we can work together for more affordable housing, stronger schools with smaller class sizes, economic and social justice, and the intangible quality of life elements that are so essential the city we love.”

The race to replace Ms. Quinn is likely to be a tight one, with Yetta Kurland, who ran against Ms. Quinn in 2009 and grabbed 31 percent of the vote gearing up to mount another run.  Brad Hoylman, a community president and lawyer with the Partnership for New York City, recently dropped out of the race to run for the State Senate in a seat being vacated by Tom Duane.

Mr. Johnson, who is chair of Community Board 4 and a former leader of GLAAD, rose to prominence when he was still in high school and he came out to his football team.

The full list of endorsers is below: