WASHINGTON (AP) — The special counsel in the Russia investigation is accusing former Trump campaign chairman Paul Manafort of violating his plea agreement by repeatedly lying to federal investigators, an extraordinary allegation that could expose him to a lengthier prison sentence — and potentially more criminal charges.

The torpedoing of Manafort's plea deal, disclosed in a court filing Monday, also results in special counsel Robert Mueller's team losing a cooperating witness from the top of Donald Trump's presidential campaign who was present for several key episodes under investigation. Tha...