CEDAR RAPIDS, Iowa — Former Vice President Joseph R. Biden Jr. found himself fending off new questions about his decades-long record on lesbian, gay, bisexual and transgender issues, in a testy exchange with a moderator who described his treatment of her as “condescending.”

During a Friday night forum focused on L.G.B.T.Q. issues, Mr. Biden seemed to recoil from the direct questioning from Lyz Lenz, a Cedar Rapids Gazette columnist.

In a question-and-answer session, Ms. Lenz repeatedly pressed Mr. Biden about his past votes for the Defense of Marriage Act, the military’s “don’t ask, don’t tell” policy that forbade openly gay people from serving and his statement earlier this year that Vice President Mike Pence, known for his socially conservative positions, was “a decent guy.”

Mr. Biden sought to defend himself, reminding the audience in a steamy auditorium that he supported same-sex marriage before President Obama. “I didn’t have to evolve,” he said.