The Justice Department has agreed to allow congressional investigators to interview a key FBI employee believed to have served as the main contact, or "handler" of, former British intelligence agent Christopher Steele, who compiled the so-called "dossier" of allegations about President Donald Trump's connections to Russia, according to a department spokesperson.

The interview, the product of a month-long negotiation, comes as a spat between Justice officials and the House Intelligence Committee has spilled into public view without much context.

Shortly after 8 p.m. Wednesday, President Donald Trump fired off a tweet taking aim at the Justice Department and FBI -- this time accusing his top law enforcement agencies of stymieing the Intelligence Committee's Russia probe.