Like with the Birther nonsense, which millions of Americans still believe. Trump will tweet/say the investigation did find voter fraud in California and New York. Regardless of whether there was any significant fraud. He will scream "fake news" or "criminal" at any individual/media organization that questions his assertions.
Those of us, capable of critical thinking, will see this as the stunt it is. But many many will not.
This is exactly how he narrowly won the election. Those that oppose Trump better figure out how to effectively counter these lies without stooping to the same tactics if they want to beat him.