This John Brennan quote on Russia just made Donald Trump's life much harder

(CNN)Former CIA chief John Brennan offered a frank assessment of Russia's aggressive approach to meddling in the 2016 election and, in the process, complicated President Donald Trump's attempts to cast the whole thing as fake news.

This Brennan quote, in particular, is damning:
"I encountered and am aware of information and intelligence that revealed contacts and interactions between Russian officials and US persons involved in the Trump campaign that I was concerned about because of known Russian efforts to suborn such individuals. It raised questions in my mind about whether Russia was able to gain the cooperation of those individuals."
Now, as Republicans on the committee were quick to note, Brennan wasn't saying that he believed that the Trump campaign actively colluded with Russia. Only that, again in his words, "I saw interaction that in my mind raised questions of whether it was collusion...It was necessary to pull threads."
    No one -- or very, very few people -- are alleging that there is any evidence at this point that proves collusion between Trump's presidential campaign and Russian intelligence operatives. What most people -- including the vast majority of Democrats -- are saying is that there is enough smoke here that a serious investigation needs to be launched into whether there is a fire somewhere.
    Contrast that with Trump's stance: That this entire proceeding -- up to and including the appointment of Robert Mueller as special counsel to oversee an independent investigation -- is a "witch hunt." That there's no truth in any of the media reports suggesting that the likes of Michael Flynn, Carter Page, Paul Manafort and Jared Kushner may have had interactions with the Russians that crossed a line.
    What Brennan laid out Tuesday is a lot closer to the former view than the latter one held by Trump. And Brennan isn't just some guy. He's not only a former CIA director under the Obama administration, but also someone with decades of experience in the intelligence world.
    This is not someone reading the papers or watching TV and making a snap judgment about Trump and the Russians. This is someone who was intimately familiar with the intelligence gathering regarding Russian attempts to meddle in the election. His voice matters more than most.
    So when Brennan says the Russian efforts to "suborn" members of the Trump campaign "raised questions in my mind about whether Russia was able to gain the cooperation of those individuals," it makes it far more difficult for Trump and his senior aides to dismiss all of the questions about Russia's involvement in the election as simply a media-created conspiracy.
    If Donald Trump is, as he has insisted since the beginning of all of this, totally innocent of any ties to the Russian meddling, he should be hugely supportive of these investigations designed to get to the bottom of it. To date, he's been the exact opposite.
    I don't know why that is. And I won't hazard a guess, either. But Brennan's testimony in regard to his suspicions about the possibility of collusion is broadly consistent with what a number of other high-profile voices -- former acting deputy Attorney General Sally Yates, former FBI Director James Comey -- have said: That the ties between Russia and the Trump campaign deserve more investigation.
    With every statement like the one Brennan made today, it makes it that much harder for Trump to sell the "total hoax" storyline on Russia's meddling. It doesn't mean he'll stop. He likely won't. But his credibility will take deeper and deeper hits if he continues to push that line in the face of lots of smart people saying there's much more to look at here.