WASHINGTON (AP) — The Justice Department’s internal watchdog is expected to criticize the FBI’s handling of the Hillary Clinton email investigation, stepping into a political minefield while examining how a determinedly nonpartisan law enforcement agency came to be entangled in the 2016 presidential race.

The inspector general’s report is set for release this afternoon. It’s likely to be painstakingly detailed, the culmination of an 18-month review into one of the most consequential FBI investigations in recent history.

President Donald Trump will look to the inspector general report to provide a fresh line of attack against two former top FBI officials, Director James Comey and his deputy, Andrew McCabe, as he claims that a politically tainted bureau tried to undermine his campaign and, through the Russia investigation, his presidency. Trump will almost certainly use the report to validate his firing of Comey last year.

But the report could do more to back Democratic claims that the FBI contributed to Clinton’s defeat, most notably by reopening in the final days of the race its investigation into whether she mishandled classified information. That development unfolded as Trump’s own campaign — unbeknownst at the time to the American public — also came under FBI investigation for possible coordination with Russia.

Inspector General Michael Horowitz, a former federal prosecutor appointed by President

Barack Obama, prepared the report. Supporters from both parties regard him as apolitical. His most significant report before this one was the 2012 study of the botched Obama-era gun operation known as Fast and Furious.