Okay. It's of course possible that McCain misspoke, although according to The Washington Post's Mike DeBonis, who was one of the reporters McCain was talking to when he unleashed this quote, McCain was given a chance to clean up the mess right then and there, and didn't:
When pressed by a reporter on the claim that Obama was “directly” responsible, McCain reiterated his point — that Obama should not have withdrawn combat troops from Iraq: “He pulled everybody out of Iraq, and I predicted at the time that ISIS would go unchecked, and there would be attacks on the United States of America,” he said. “It’s a matter of record, so he is directly responsible.”
I don't have the ability to crawl into McCain's brain and see exactly what he meant at the moment. But, I do think that it's not unreasonable to see Trump's influence — both on political rhetoric and on Republican politics — here.
Trump has turned rhetorical excess into an art form. He says and does things that other politicians won't and, in so doing, dominates the conversation virtually every day. The effect of Trump's willingness to "go there" rhetorically is that it ups the ante for every other Republican when asked about, say, President Obama.
"He's a good man, but I disagree with his policies" is no longer the sort of thing a GOP pol can say. When you have your presumptive presidential nominee insisting that Obama should resign within 24 hours of the Orlando shooting, there is an expectation from the party base that you match that rhetoric.
McCain has shown a penchant for channeling the base's sentiments in the past. Remember "complete the dang fence" during his 2010 primary fight against former Rep. J.D. Hayworth? That, of course, came just a few years removed from McCain's leading role in one of the first attempts at comprehensive immigration reform.
Which brings me to the political influence that Trump is bringing to bear on McCain. Like in 2010, McCain faces a primary challenge. Unlike 2010, it appears to be a more serious one — in the form of physician and former state senator Kelli Ward. A PPP poll released last month showed McCain at 39 percent to Ward's 26 percent. And there were plenty of other warning signs for the incumbent. Just 1 in 3 (35 percent) of Republican voters approve of the job he is doing; among those who identify themselves as "very conservative," that approval rating is a dismal 18 percent.
McCain has never been the best friend of the Republican base. But the rise of Trump has massively emboldened a segment of the GOP base that are not, to put it mildly, McCain voters. McCain is, of course, aware of how Trumpism works against him in a Republican primary. And he also knows that the quickest way to Republican base voters' hearts is via some bashing of President Obama.
2+2 = McCain on Thursday.
Whether or not Trump wins the White House, he already has had a profound effect on American politics generally and the Republican Party more specifically. McCain's comments reflect that influence — whether the Arizona senator realizes it or not.