As Rep. Devin Nunes (R-CA) continues to use his position as the leader of the House Intelligence Community to undermine the Justice Department’s investigations in President Donald Trump and associates, the Washington Post reports that the chairman’s efforts recently crossed a dangerous line.

According to a Tuesday report, department officials warned the White House last week that Nunes’ latest request for information could expose a sensitive intelligence source, who is a U.S. citizen. The report says that Justice Department officials believe that multiple lives would be at risk if this person’s identity were exposed.

Officials were able to convince the White House, up to and including the president, to block Nunes’ request, the Post found. But, it notes, it is not clear that Trump was fully aware of all the details about sources’ history, including that they have provided information to special counsel Robert Mueller’s Russia investigation team.

“This game Devin Nunes is playing at isn’t actually a game,” said legal analyst Susan Hennessey in response to the report. “[It] has real consequences and risks endangering the lives of intelligence sources.”

Nunes, who is a close ally of the president, has attempted to undermine the Mueller’s investigation and the leadership of the Justice Department. These efforts have paralleled the president’s rhetorical attacks on Mueller, as well as the attorney general and deputy attorney general.