As described by sources familiar with various aspects of the investigation, the Mueller probe is fast approaching a critical crossroads. The president’s lawyers, Ty Cobb and John Dowd, are pressing Mueller to wind down the investigation and exonerate their client, which they have assured the president will happen by early next year.

But the sources familiar with the probe say that such a rapid conclusion is — as one put it — “fanciful.” Mueller and his team, they say, are pursuing new leads, interrogating new witnesses and collecting a mountain of new evidence, including subpoenaed bank records and thousands of emails from the campaign and the Trump transition.

In just the last few weeks, his prosecutors have begun questioning Republican National Committee staffers about the party digital operation that worked with the Trump campaign to target voters in key swing states. They are seeking to determine if the joint effort was related to the activities of Russian trolls and bots aimed at influencing the American electorate, according to two of the sources.