WASHINGTON — The Justice Department’s top watchdog will review why the F.B.I. scuttled plans to erect a new headquarters in suburban Washington and instead chose to replace the J. Edgar Hoover Building on its current site near the White House, he wrote to lawmakers this week.

The F.B.I.’s abrupt change of plans has fueled concerns among Democrats in Congress that President Trump personally intervened to make sure that the land was not redeveloped with a project that would compete with his company’s nearby hotel. In May, Democrats asked the Justice Department’s inspector general, Michael E. Horowitz, to examine the decision.

“For months, our committees have investigated the administration’s sudden change of heart on a federal property across the street from the president’s namesake hotel, but because the F.B.I. has withheld key decision-making documents from Congress, we have been left with many unanswered questions,” the Democratic heads of four House committees and subcommittees said on Wednesday in a statement. “We welcome the I.G.’s independent examination, which will supplement our ongoing effort to get to the truth.”

The F.B.I. had been moving toward relocating to a campus in suburban Maryland or Virginia while also planning to move potentially thousands of bureau employees to Huntsville, Ala., where the F.B.I. already has a sizable presence and space for more people.