WASHINGTON (Reuters) - Talks over whether the whistleblower who sparked an impeachment inquiry into U.S. President Donald Trump will testify to Congressional committees are hung up on the question of whether the person can submit written testimony, two sources familiar with the discussions said.

Negotiators in the Democratic-led U.S. House of Representatives are open to the career intelligence officer making written testimony while negotiators in the Republican-majority Senate have resisted, said the sources.