If the investigation will clear Trump, then why is he trying to discredit the intelligence community?
He claims the Russians weren't behind the DNC hacking--how would he know, without an investigation? 

John McCain and Lindsey Graham owe Trump nothing. McCain is probably in his last term in the Senate, he can make Trump's life living hell, by launching one investigation after another.  What's really surprising is that Mitch McConnell appears to be onboard. Buy popcorn futures and stirthepot!