Joe Biden has been seen as a gaffe machine for a long time – at least as far back as his campaign to be Barack Obama’s vice president. But instead of fine-tuning his public speaking skills and trimming his speeches of the kind of fat likely to get him mocked and, sometimes, in worse trouble, he appears to be getting more prone to these gaffes with every passing day. While his campaign is trying desperately to present these flubs as “part of his charm,” it’s not quite clear if that’s how the electorate will view them in the long run. There comes a point where voters will have serious doubts about Biden’s mental fitness and his ability to handle one of the most stressful, difficult jobs in the world.

That point may have already come, because the last week has been one of Biden’s worst. And we’re not just talking about slips of the tongue here. We’re talking about blatant lies like the largely-fictional story he told about visiting Afghanistan in honor of a Navy Captain who had risked his life to bring his dead colleague out of a war-torn area.

“We can lose a vice president,” Biden told the audience solemnly. “We can’t lose many more of these kids. Not a joke.”

Despite telling the audience that they had his “word as a Biden” that this story was the “God’s truth,” the Washington Post quickly determined that it was anything but.

“Almost every detail in the story appears to be incorrect,” they reported.

It’s difficult to find examples of liberal media hosts going in on the Great White Democratic Hopes, but this one was too much for even MSNBC’s Chris Matthews, who said: “I mean, he’s not Ernest Hemingway. You don’t get to make it up based upon facts. You have to have the facts.”

Biden also said last week that he’s not familiar with Boris Johnson.

“I don’t know the new prime minister of England,” Biden said in South Carolina. “He looks like Donald Trump, I know that.”

Johnson, of course, has been a prominent UK politician for a very long time. In fact, he was the mayor of London when Biden was vice president. This means that Biden is either very ignorant when it comes to international politics or that he’s just once again flubbing it as he goes along.

Whether these gaffes speak to Biden’s deteriorating mental state or are just part of his personality, they are not an asset by any means. If they don’t begin to force voters to question his fitness for office, they will at least undermine the seriousness with which he can be taken as a candidate.

That leaves him ripe for the picking in the general election…if he can even stumble his way there in the first place.