Joe Biden’s presidential campaign is a train wreck of gaffes and mental lapses. His tendency to fuck up during every public appearance has garnered significant attention from the media, sometimes played for laughs and sometimes reported with genuine concern. He seems to be legitimately unwell, and his declining polling numbers show that people are noticing.

But the sheer frequency of his mental errors has masked a far more sinister and intentional habit, one that’s been core to his entire political career: Joe Biden can’t stop lying.

Tuesday morning, soon after being caught inventing a story about a soldier in Afghanistan, Biden lied to an NPR reporter about his support for the Iraq War. In Biden’s version of events, he began to oppose the war as soon as George W. Bush’s brutal “shock and awe” campaign began: “Immediately, that moment it started, I came out against the war at that moment.”

In fact, Biden was still defending his vote to authorize the war five months after the invasion (“I would vote that way again today . . .  it was a right vote then, and it’ll be a right vote today,” he told the Brookings Institution in July 2003), and he continued to support the war for the rest of his Senate career, even opposing efforts to set a timetable for withdrawal. Not to mention that he was one of the war’s most enthusiastic backers in the Democratic Party who played a key role in partnership with the Bush administration in selling the war to the American people, as Branko Marcetic has detailed.

As if that lie weren’t enough for one week, Biden followed with a second during Wednesday’s nationally televised climate town hall. Called out by an audience member on his plans to attend a high-dollar fundraiser hosted by the founder of a fossil fuel company, Biden denied the accusation.

“I just want to be very clear to everyone here: I am committed to not raising money from fossil fuel executives, and I am not doing that tonight,” he told the questioner.

Quickly corrected by host Anderson Cooper, he then apologized and pleaded ignorance. Biden attended the fundraiser the next day, anyway.

Add these to the growing list of falsehoods Biden has told over the course of his campaign and career. He’s lied to downplay his role in silencing Anita Hill during Clarence Thomas’s confirmation hearing. He’s lied about his anti-school integration position and about his fondness for segregationist colleagues. He’s faced multiple plagiarism scandals. He’s denied wanting to cut Social Security and Medicare. And of course, he’s parroted a series of industry lies about Medicare for All, the single-payer policy championed by Bernie Sanders, his closest primary competitor.

Combined with his declining mental faculties, Biden’s dishonesty makes for a painful campaign to watch. He may not be sniffing women’s hair anymore, but every day he’s either forgetting Barack Obama’s name (or, alternatively, referring to the former president as “Raprock”), stumbling through a completely incoherent speech, or mistaking what state he’s currently in.

This behavior seems to be harming Biden’s frontrunner status. His polling average has steadily dropped by over ten points since May, and his allies are now scrambling to limit his public exposure. He’s lost top donors and the support of key Obama staffers. Obama’s chief strategist David Axelrod has even taken to publicly criticizing him.

But it’s the lies, not the gaffes and mental lapses, that show us the real Joe Biden. Even if by some miracle his brain improves, the blabbering stops, and the errors cease, we’ll still be left with his blatant falsehoods and the reactionary politics they’re meant to hide.

Biden lies to protect billionaires’ profits, and he lies because the truth about his record is damning. Joe Biden has told so many lies in the past that he now has to tell new lies to keep his lie-based campaign afloat. If he were to quit lying, he’d have to answer for who he actually is: a happy stooge of industry who uses his political power to squash working-class demands for a better society in their tracks.

In a just world, Biden’s political career would have ended decades ago, or he’d be in prison alongside Bush, Dick Cheney, and everyone else who helped launch an illegal war that slaughtered hundreds of thousands of people and will likely leave much of the Middle East drenched in blood for decades to come. Instead, he’s leading the pack in his third presidential campaign. His steady fall in the polls is encouraging, and he’s not helping his own case with his public appearances.

But Biden’s mental blunders don’t change what has always been his real problem and the key to defeating him: his politics are god-awful, and he can’t stop lying about them.