From AP on Yahoonews:

Trump cites voter fraud in NH without providing evidence

It's the second time Trump has used a bipartisan meeting with lawmakers to make erroneous claims about voter fraud. Last month, during a bipartisan congressional leadership meeting at the White House, he claimed that he would have won the popular vote if not for 3 million to 5 million immigrants in the country illegally voting for his Democratic opponent, Hillary Clinton.

I know this is ridiculous for all the obvious reasons, but here is one more reason.  3 million to 5 million people is a lot of people.  You would notice 3 million to 5 million people.

I'm reminded of a debate I used to get into when I lived in Cambodia.  During election time, the opposition would play off of the anti-Vietnamese sentiment in Cambodia, and there was a rumor that the government had brought in 2 million Vietnamese people to illegally vote in the election.

I know it sounds ridiculous, but the current Cambodian government was so unpopular that people were willing to believe they were capable of anything.  I knew several people, both Westerners and Cambodians, who believed this.

I used to get into the debate frequently.
"Okay," I used to say.  "How many people would fit on a bus?  20, say?  So to get 2 million Vietnamese over here, that would be 100,000 buses crossing the boarder on election night?  There's no way that could have gone unnoticed."

The same comments could be made about Trumps imagined 3 to 5 million illegal immigrants voting.