After hearing that President Trump had fired FBI Director James Comey, Senator John McCain said he was “disappointed” and warned that there are, “more shoes to drop.”

Shortly after hearing the news that President Trump had fired FBI Director James Comey, Senator John McCain said he was “disappointed,” reports Time.
The Week notes that, later, when speaking at an off-the-record meeting of foreign diplomats, "...McCain elaborated, saying Trump could not escape the specter of the Russia investigation even after firing Comey..."
According to the Washington Post, McCain told the group, “This scandal is going to go on. I’ve seen it before. This is a centipede. I guarantee you there will be more shoes to drop, I can just guarantee it. There’s just too much information that we don’t have that will be coming out.” 
McCain also called the firing “unprecedented” and “unfortunate” and noted, “The president does have that constitutional authority. But I can’t help but think that this is not a good thing for America.” 
As he has in the past, McCain recommended that the investigation into Russia’s involvement in the 2016 election be conducted by an as yet to be established special congressional committee. 
Meanwhile, Trump defended his decision to fire Comey on Twitter.
He tweeted Wednesday, "Comey lost the confidence of almost everyone in Washington, Republican and Democrat alike. When things calm down, they will be thanking me!" and "James Comey will be replaced by someone who will do a far better job, bringing back the spirit and prestige of the FBI."