I think perhaps the thing they didn't count on, was the level of cheating at multiple levels. Homegrown, China, Dominion, hacking....etc.

This is why Trump is confident, yet pissed. He probably thought that it could all get settled in the two month period before the inauguration, but because of just the absolute shit show it was, it was impossible to put the pieces together in that amount of time.

Trump is pissed and talking more now, because he sees how dire the situation is for America and this plan is taking a tad longer then he hopped it would take.

Well this my theory :P