White House lawyers are expected to meet with special counsel Robert S. Mueller III’s office late this week seeking good news: that his sprawling investigation’s focus on President Trump will soon end and their client will be cleared.

But people familiar with the probe say that such assurances are unlikely and that the meeting could trigger a new, more contentious phase between the special counsel and a frustrated president, according to administration officials and advisers close to Trump.

People with knowledge of the investigation said it could last at least another year — pointing to ongoing cooperation from witnesses such as former Trump campaign adviser George Papadopoulos and former national security adviser Michael Flynn, as well as a possible trial of two former Trump campaign officials. The special counsel’s office has continued to request new documents related to the campaign, and members of Mueller’s team have told others they expect to be working through much of 2018, at a minimum. 

The dynamic threatens to intensify the already inflamed political atmosphere enveloping the investigation into Russia’s meddling in the 2016 election. Even as White House lawyers have pledged to cooperate with Mueller, Trump and his allies have accused the Justice Department and FBI of bias and overreach.