Representative Charlie Rose (D-N.C.) is launching a campaign for House Speaker--even though Thomas S. Foley (D-Wash.) isn't leaving his post. To pressure Foley to move aside, Rose, chairman of the House Administration Committee, has created a leadership PAC to funnel campaign contributions to colleagues. Members say Rose has spread reports that Foley might be named ambassador to Britain, a post likely to go to Admiral William Crowe (Ret.). Rose has asked for support in a race for Speaker against Majority Leader Richard A. Gephardt (D-Mo.), the favorite if Foley steps down.