"I think it's fine," Ryan said in an interview on MSNBC's "For The Record."
"First of all, I'm sure there is some fraud," he said. "If he believes there's a problem to be looked at, the right thing to do is get the evidence, the facts."
Ryan cited voter ID laws in Wisconsin as measures he said were passed due to concerns about election fraud. Earlier Wednesday, White House press secretary Sean Spicer suggested that the Trump administration could view such laws as a solution to Trump's invented problem.
Ryan also admitted that he has no evidence of fraud on the scale that Trump has alleged.
"I haven't seen evidence of this kind of widespread numbers that we've been hearing about," he said.
"He has made it sound like that's why he lost the popular vote," Greta Van Susteren asked. "Do you believe that?"
"He is President of the United States," Ryan replied. "I think that speaks for itself."