WaPo:

Attorney General William P. Barr imposed new rules Tuesday tightening the use of government surveillance on political candidates or their staffers — a move likely to cheer conservatives who have long criticized how the FBI investigated the Trump campaign in 2016.

In a pair of memos, the attorney general said that before the FBI and Justice Department seek a warrant from the Foreign Intelligence Surveillance Court to secretly monitor the communications of an elected official, a declared political candidate, or any of their staff, official advisers or informal advisers, officials must first consider warning that person that foreign governments may be targeting them, and if they choose not to give such a warning, the FBI director must spell out in writing the reasons for not doing so.

Barr’s memos speak directly to one of the biggest complaints about the FBI made by President Trump and his supporters — that agents wrongly surveilled former campaign aide Carter Page in 2016.