WASHINGTON — A federal judge in Washington has extended the term of a grand jury hearing evidence uncovered by the special counsel, Robert S. Mueller III, in his investigation into Russia’s interference in the 2016 presidential race and the Trump campaign.

The jurors, impaneled in July 2017, will continue to meet for up to six months. Beryl A. Howell, the chief judge of the Federal District Court in Washington, approved the extension ahead of the scheduled expiration of the grand jury’s term this week.

The extension underscores that Mr. Mueller’s team continues to pursue leads about Russia’s covert effort to influence the results of the 2016 election, and whether anyone in the Trump campaign conspired with Moscow to help Donald J. Trump triumph over Hillary Clinton.

The prosecutors working for Mr. Mueller are believed to be writing a report for senior Justice Department officials summarizing their findings, but it is unclear how detailed it will be or how or whether it will be made public, including whether the White House could interfere with its release. Representative Jerrold Nadler, Democrat of New York and the new chairman of the House Judiciary Committee, told CNN on Friday, “We will make sure it is public.”