WASHINGTON (AP) — President Donald Trump's former campaign chairman Paul Manafort agreed Friday to cooperate with the special counsel's Trump-Russia investigation as he pleaded guilty to federal crimes and avoided a second trial that could have exposed him to more time in prison.

The deal gives special counsel Robert Mueller a key cooperator who steered the Trump election effort for a pivotal stretch of the 2016 presidential campaign. The result also ensures the investigation will extend far beyond the November congressional elections despite entreaties from the president's lawyers that Muelle...