As the Trump administration’s saber-rattling toward Iran threatens another disastrous war in the Middle East, foreign policy has gained newfound focus in the 2020 presidential race. And former vice president Joe Biden’s 2002 vote in favor of the Iraq War leaves him with a particularly glaring vulnerability.

Biden’s vote had already become a sticking point in the race before President Trump began his provocations toward Iran in earnest. Bernie Sanders has used Biden’s record to draw a contrast with his own opposition to the Iraq War. Rep. Seth Moulton, another 2020 candidate, has called for Biden to admit he was wrong for casting the vote. And a recent POLITICO/Morning Consult poll showed more than 40 percent of respondents between eighteen and twenty-nine were less likely to back Biden because of it.

But to say the now–Democratic front-runner voted for the Iraq War doesn’t fully describe his role in what has come to be widely acknowledged as the most disastrous foreign policy decision of the twenty-first century. A review of the historical record shows Biden didn’t just vote for the war — he was a leading Democratic voice in its favor and played an important role in persuading the public of its necessity and, more broadly, laying the groundwork for Bush’s invasion.