Transcript for Alleged Voter Fraud Continues to Be a Top Issue for Trump
President trump taking air force one for the first time today, and at one point allowing cameras on board. He was on his way to meet with members of congress. Republicans who now, of course, control the house and the senate. When he arrived he talked about many things, including his new investigation into voter fraud after claiming millions of illegal votes cost him the popular vote. After we asked him last night here, where's the evidence? Here's ABC's Cecilia Vega in Philadelphia. Reporter: Tonight, president trump inviting the cameras into the private cabin on air force one. Great plane really beautiful. Reporter: Showing off his new flying office. This is a very special plane for a lot of reasons. Reporter: Emerging from his first flight, a sharp salute. The president on a charm offensive. Making nice with Republican lawmakers at their retreat in Philadelphia, the party now controls congress and the white house. Nice to win. Do we agree? It's been a while. It's been a while since we had this position. Nice to win. Reporter: His goal, to win support for his sweeping agenda. But today he kept pushing an issue congressional Republicans want to go away, the false claim that millions voted illegally in the election. We are going to protect the integrity of the ballot box, and we are going to defend the votes of the American citizen. So important. Reporter: But house speaker Paul Ryan has been clear saying he has seen no evidence of massive voter fraud. David asking, now that the president is in the white house, is it dangerous to make claims without concrete proof? Do you think that your words matter more now? Yes, very much. Do you think that talking about millions of illegal votes is dangerous to this country, without presenting the evidence? Not at all. Many people feel the same way -- You don't think it undermines your credibility? Reporter: Some Republicans say there are more important things to worry about. Should it be on the list of things he was talking about today? Is it in the top ten priorities? The answer is no. It's up to the administration. Reporter: Republicans also not interested in revisiting the election. Or the size of the crowds at the president's inauguration. Something president trump has talked about again and again, including at the CIA. You took some heat after your visit to the CIA in front of that hallowed wall. 117 stars of those lost at the CIA. You talked about other things, but you also talked about crowd size at the inauguration. About the size of your rallies, about covers on "Time" magazine, and I want to ask you, when does all of that matter just a little less? When do you let it roll off your back? I'm glad you asked. I went to the CIA, my first stop. I have great respect for people, and the intelligence and CIA. I paid great homage to the wall, and I spoke to the crowd. I got a standing ovation. They said it was the biggest standing ovation since Peyton manning had won the super bowl, and they said it was equal. I got a standing ovation that lasted for a long period of time. And Cecilia Vega with us live in Philadelphia tine. The president telling me that the investigation had been launched. He said, done. Regardless of proof of any fraud. What are you learning tonight? Reporter: Not so fast, David. The president was expected to sign an order to launch the investigation. That did not happen. The white house does tell us it will happen in coming days.
This transcript has been automatically generated and may not be 100% accurate.