The Justice Department submitted the evidence to the committee this afternoon.
Reuters: Justice Department delivers documents on wiretap claim to Congress
You forget that the President CAN'T reveal "evidence" that reveals classified information or clandestine sources and methods. What Trump CAN do is continue to quote the media back at them, which is what he's doing, with absolute confidence in his assessment, while he lets the investigation proceed.
The moment he got close to revealing specifics, that Democrat weasel Adam Schiff jumped on him. Read this carefully. Rep. Schiff: Trump Might Have Leaked Classified Info on TV
So they thought they had him in a pincer - they KNOW he has the evidence, and they ALSO KNOW he can't say what it is.
So he is on solid ground by quoting public sources. Which is what he is doing.
The President is allowed to de-classify whatever he wants
http://www.politico.com/story/2017/03/tom-cole-trump-should-apologize-obama-wiretapping-claim-236170
GOP Rep. Tom Cole: Trump owes Obama an apology for wiretapping claim