DETROIT — There may be no "Ready for Biden" campaign here, prodding the vice president to launch a third bid for the presidency, but he received an enthusiastic welcome Thursday by the nation’s largest gathering of liberal activists.The voluble Biden – who gets eclipsed by Elizabeth Warren and Hillary Clinton in the hearts of many of the activists – got love for his "candor," and a salute for prodding President Barack Obama into endorsing gay marriage."Those of us who hold marriage equality near and dear to our hearts and our homes, we know Joe Biden spoke first," said Arshad Hasan, the executive director of ProgressNow, as he introduced Biden to the stage. "I give Joe Biden credit for changing the dialogue in the White House."Biden, who arrived late after consulting with Obama and the national security team over the downing of a plane over Ukraine, demurred only a bit."I’m flattered," said Biden, who beat Obama to the punch in 2012, saying on Meet the Press that he supported same-sex couples getting married. Three days later, President Obama announced that after "evolving" he would back gay marriage.Biden said his remarks on Meet the Press weren’t planned, "but when I get asked a direct question, I give a direct answer. I come out of civil rights movement, there’s not a way I could sit there and be asked about the civil rights issue of our day and not be silent."But Biden, who said Obama “fully agreed with me,” credited the lesbian, gay and transgender community "for moving things along. The credit really goes to the community."The appearance was Biden’s first before the influential group and comes as Biden is widely viewed as wanting to keep his name in play for 2016 and making a play to Clinton’s left flank.He presented his liberal credentials to attendees, recalling his fights against conservative Supreme Court nominees.But any Biden candidacy would be viewed as an extension of the Obama tenure and protesters disrupted Biden’s appearance, shouting "Don’t Deport our families."As they were escorted out, Biden said he empathized with their plight."Can you imagine the pain, the anxiety of coming home every day wondering whether your mother or father is there? Can you imagine what it would feel like," he said.Clinton is not appearing at the convention, though her campaign-in-waiting, Ready for Hillary, has a presence -- providing snacks at lunchtime to hungry activists. Warren -- who says she’s not running for president but has also inspired a “Ready for Warren” group -- is scheduled to deliver the keynote address on Friday.