CNN's "Reality Check" column scoffed at the claim: "There was the bad microphone, which no one, except for him, seemed to notice."
The aptly named (in this case) Mic.com interviewed an audio expert who said: "The professional audio community has largely been dismissive of the possibility of a mic problem."
Hillary Clinton even goofed on him: "Anybody who complains about the microphone is not having a good night."
On Friday afternoon, the Commission on Presidential Debates confirmed that Trump did indeed have a microphone that was at least somewhat defective.
"Regarding the first debate, there were issues regarding Donald Trump's audio that affected the sound level in the debate hall," the commission said in an unfortunately brief one-sentence statement.
Vindication for Trump? Certainly some, yes. But not completely.
The thing about Trump's microphone claim is that he didn't just say his microphone was bad; in his trademark fashion, he took it three steps further, suggesting that it was done as part a conspiracy against him — the rigged system and all that.
"I don't know if you saw that in the room, but my microphone was terrible," Trump said the next morning on "Fox and Friends." "I wonder, was it set up that way on purpose?"
He said in the spin room after the debate: "And they also had — gave me a defective mic. Did you notice that? My mic was defective within the room. No, but I wonder, was that on purpose? Was that on purpose?"
Trump suggesting a defective microphone as an excuse for a poor debate performance is one thing; Suggesting that same microphone was part of a plot to take him down is another thing entirely.
Of course, if he had just stopped at the faulty microphone claim, he might have still drawn derision. Merely bringing it up afterward suggested he was blaming it for his poor performance, even though it's not clear how much it might have actually hindered Trump. His microphone for the broadcasts was working fine, which means that the vast majority of the people who were watching could hear him fine. The relatively minuscule number of people inside the debate hall are unlikely to decide who the next president is — especially given they were in a blue state, New York.
But it's also possible that the microphone issues could have been a distraction for Trump — something you don't need when you're on stage in front of tens of millions of people in your first general-election debate for president of the United States. It's also possible that it didn't distract him at all and he was just using it as an excuse. We can't put ourselves in his shoes that night.
Trump supporters will undoubtedly seize upon this as proof that the media is too quick to doubt Trump's allegations and that we all sought to cover up the defective microphone. After all, he was right! And thus he's probably right about all the other things that the media heaps doubt upon!
And perhaps, in this case, the doubt was premature. It sure would have been nice for the commission to say something earlier in the week. Now we have a situation in which Trump supporters will be full of righteous indignation. And they'll have some reason to be — at least in this one case.
But Trump's suggestion that this was part of a campaign against him is still a conspiracy theory. And given his embrace of so many conspiracy theories, it's not hard to see why the reaction to his microphone claim was so skeptical.