Mulvaney's bid to join impeachment lawsuit challenged

White House acting chief of staff Mick Mulvaney is facing opposition, including from a former Trump administration adviser, in his bid to join a lawsuit over testimony in the House impeachment inquiry.The opposition from Charles Kupperman, the former deputy national security adviser who sued over a subpoena from the House, underscores the lack of a unified approach from Trump administration officials in responding to the impeachment inquiry, which enters a critical public phase this week.Several