He made a very tired joke
Nobody laughed when he first said it on a Tuesday, and at his first chances to clarify it he doubled down on it, it took until Thursday before he claimed was a joke. Here's what happened in between:
From the Washington Post:
1. Trump campaign officials never said he was joking on Wednesday. They mounted a robust defense, mind you, but they didn't say it was a joke.
2. Trump doubled down. In a tweet after the comments exploded on social media, Trump sought to explain a little bit â" apparently suggesting he simply meant that the emails should be turned over to the FBI "if Russia or any other country or person has" them. Again, no mention of joking around.
3. He said it twice. This wasn't a one-off quip in Trump's news conference on Wednesday. He initially said he hoped the Russians had the emails, and then he returned later to say that if they didn't have them, he hoped they would obtain them.
4. A reporter gave him an out -- that he didn't take. NBC's Katy Tur, later in Wednesday's press conference, basically asked Trump twice if he was serious. In response, Trump indicated he had no qualms about, in Tur's words, "asking a foreign government â" Russia, China, anybody â" to interfere, to hack into the system of anybody's in this country."
Lastly, even though very clearly he wasn't joking, even as a joke this is wholly unpresidential. So to sum it up, he clearly wasn't joking and even under this absurd excuse concocted two days after the fact Trump still loses points with this one, As simple as that. And all around fscked up for him anyway you see it.
But as Trump himself said, he could go and shoot someone in Times Square and his voters would still support him. That part he did get right.