F.B.I. Agent in Russia Inquiry Saw Basis in Early 2017 to Doubt Dossier

While Mr. Strzok was still working on other aspects of the larger Russia investigation, he was not part of the team working on the wiretap renewals, his lawyer said. Another senior F.B.I. counterintelligence official, Jennifer Boone, was supervising a team in charge of determining the sources of information for the dossier and of handling the wiretap targeting Mr. Page, according to people familiar with the investigation.

Mr. Strzok was later removed from the Russia investigation after the Justice Department inspector general discovered numerous texts on his work phone expressing animus toward the election of Mr. Trump. The inspector general, however, did not find evidence that he took or withheld any official action because of his personal opinions.

Mr. Strzok’s skeptical annotations of the Times article, headlined “Trump Campaign Aides Had Repeated Contacts With Russian Intelligence,” were similar to congressional testimony months later by the former F.B.I. director James B. Comey disputing it. Mr. Comey did not say exactly what he thought was incorrect about the article, which cited four current and former American officials who spoke on the condition of anonymity to discuss classified information.

Mr. Strzok’s annotations disputed the article’s premise and other aspects. He wrote, “We are unaware of ANY Trump advisers engaging in conversations with Russian intelligence officials.”

Still, he also added, the bureau had identified contacts between Mr. Page and Russian intelligence officials before the campaign; contacts between an associate of Paul Manafort, the onetime campaign chairman, and Russian intelligence; and contacts between two campaign advisers, Jeff Sessions and Michael T. Flynn, and Russia’s ambassador to the United States.

Eileen Murphy, a Times spokeswoman, said, “We stand by our reporting.”

The wiretapping of Mr. Page was a small part of the overall investigation into Russia’s covert attempt to help tilt the election in Mr. Trump’s favor and whether any Trump campaign affiliates had conspired in that effort. The inspector general report found that the opening of the investigation met legal standards and that the Steele dossier had played no role in that decision; the agents working on it did not learn of its existence until later.

Still, the inspector general report’s uncovering of serious flaws in the wiretap applications — including numerous errors and omissions, among them the failure to alert the court to the doubts raised by the interview of Mr. Steele’s source — has made them a political focus.