Cyndi Lauper, center, with Attorney General Eric Holder and Health and Human Services Secretary Kathleen Sebelius. (Jeff Dayak)

For two celebrated gay-rights champions, it was a coincidence they happened to be in Washington the day President Obama voiced his support for same-sex marriage — but a happy coincidence.

“It’s been a really great, amazing day,” Cyndi Lauper told us on Wednesday. She dabbed at her dark lashes. “I couldn't have been prouder to be an American. I think my president kicks butt.”

Praise for Obama’s statement was particularly loud from Hollywood — producer Norman Lear sent a big check to the reelection campaign, the NY Times reported; Ellen DeGeneres devoted a segment of her talk show to the news; and it assured a warmer welcome for the president at George Clooney’s star-studded $12 million fundraiser in L.A. Thursday night.

Billie Jean King with Mark Ein (Rich Kessler )

Lauper, the ’80s pop diva, was in D.C. to headline the Substance Abuse and Mental Health Services Administration’s “Heroes of Hope” program at G.W.’s Lisner Auditorium. Her agenda that night was her longtime advocacy for homeless teens struggling with their sexuality — but the Obama announcement sent reporters scurrying to Lisner to get her reaction. She met them in a plush dressing room, petite in a black pantsuit, a platinum corona of hair, a slash of red lipstick. Cameras for her reality TV show circled.

Were the president’s words enough? “It’s a step,” she told us. “I think it’s positive. . . It’s an evolution. It’s going to be an education.” Lauper, who is straight and married, wondered aloud whether gays are paying taxes than they should vis-a-vis their rights. “Should you give them a tax break because they’re without the right to get married?”

Billie Jean King, in town talking about making tennis more accessible, was delighted to switch topics when we asked.

“I’m thrilled! I’ve been waiting!” she told us Thursday, after a luncheon Q&A hosted by Washington Kastles owner Mark Ein. “I’m a lesbian, so of course I’m for it.”

King, 68, was the first top female athlete to come out of the closet in 1981. She’s been an outspoken advocate for gay rights ever since; in 2009, President Obama awarded her the Medal of Freedom. She said she discussed the issue with him when they first met. “I think he’s done the right thing, and I think it’s going to prove to be the right thing when he wins the election in November.”

King lives in NYC with her partner of 32 years, former tennis pro Ilana Kloss. Plans to wed?

“I don’t know,” she said. “I feel married, I guess. She’s my life, she’s it. I’ve had a ring on forever. It’s a done deal.”