WASHINGTON — From the beginning, John H. Durham’s inquiry into the Russia investigation has been politically charged. President Trump promoted it as certain to uncover a “deep state” plot against him, Attorney General William P. Barr rebuked the investigators under scrutiny, and he and Mr. Durham publicly second-guessed an independent inspector general and traveled the globe to chase down conspiracy theories.
It turns out that Mr. Durham also focused attention on certain political enemies of Mr. Trump: the Clintons.
Mr. Durham, the U.S. attorney in Connecticut assigned by Mr. Barr to review the Russia inquiry, has sought documents and interviews about how federal law enforcement officials handled an investigation around the same time into allegations of political corruption at the Clinton Foundation, according to people familiar with the matter.
Mr. Durham’s team members have suggested to others that they are comparing the two investigations as well as examining whether investigators in the Russia inquiry flouted laws or policies. It was not clear whether Mr. Durham’s investigators were similarly looking for violations in the Clinton Foundation investigation, nor whether the comparison would be included or play a major role in the outcome of Mr. Durham’s inquiry.
The approach is highly unusual, according to people briefed on the investigation. Though the suspected crimes themselves are not comparable — one involves a possible conspiracy between a presidential campaign and a foreign adversary to interfere in an election, and the other involves potential bribery and corruption — and largely included different teams of investigators and prosecutors, Mr. Durham’s efforts suggest the scope of his review is broader than previously known.
Mr. Durham’s focus on the Clinton Foundation inquiry comes as concerns deepen among Democrats and some former Justice Department officials that his investigation is being weaponized politically to help Mr. Trump. Congressional Democrats last week called on the department’s inspector general to investigate whether Mr. Durham’s review was free from political influence after his top aide abruptly resigned, reportedly over concerns that the team’s findings would be prematurely released before the election in November.
The Clinton Foundation investigation began about five years ago, under the Obama administration, and stalled in part because some former career law enforcement officials viewed the case as too weak to issue subpoenas. Ultimately, prosecutors in Arkansas secured a subpoena for the charity in early 2018. To date, the case has not resulted in criminal charges.
Some former law enforcement officials declined to talk to Mr. Durham’s team about the foundation investigation because they felt the nature of his inquiry was highly unusual, according to people familiar with the investigation. Mr. Durham’s staff members sought information about the debate over the subpoenas that the F.B.I. tried to obtain in 2016 and have also approached current agents about the matter, but it is not clear what they told investigators.
A spokesman for Mr. Durham declined to comment.
“The Clinton Foundation has regularly been subjected to baseless, politically motivated allegations, and time after time these allegations have been proven false,” the foundation said in a statement.
Right-wing news media and prominent Republicans have long promoted a narrative that the F.B.I.’s leadership and the Justice Department under the Obama administration were biased in favor of Hillary Clinton. They have accused agents and prosecutors of aggressively investigating Mr. Trump and his associates — ignoring evidence to the contrary — while moving more cautiously on allegations of corruption at the Clinton Foundation and Mrs. Clinton’s use of a private email server to conduct government business while she was secretary of state.
“There was a clear double standard by the Department of Justice and F.B.I. when it came to the Trump and Clinton campaigns in 2016,” said Senator Lindsey Graham of South Carolina, the Republican chairman of the Senate Judiciary Committee and a staunch supporter of Mr. Trump.
In the Russia investigation, F.B.I. officials did take aggressive steps such as obtaining a secret wiretap to eavesdrop on a former Trump adviser. But they also moved quietly, deploying informants and an undercover agent in part to keep the existence of the investigation from becoming public and affecting the 2016 election.
Mr. Barr has repeatedly attacked the Russia inquiry as Mr. Durham has investigated it, calling it “one of the greatest travesties in American history” and ignoring a policy that generally prohibits the department from making public statements about current investigations. Mr. Barr’s statements have raised hopes among the president’s supporters that Mr. Durham will unearth evidence of a plot to sabotage Mr. Trump’s campaign and presidency.