FORT DODGE, Iowa, Jan. 14 — Former ambassador Carol Moseley Braun plans to drop out of the race for the Democratic presidential nomination and endorse Howard Dean on Thursday, giving him an important symbolic boost just four days before Iowa's leadoff caucuses, Dean campaign aides said on Wednesday. Ms. Braun, a former senator from Illinois and ambassador to New Zealand and Samoa, had failed to garner much money or support in polls, but had distinguished herself with eloquent performances in several nationally televised debates. She and Dr. Dean, the former governor of Vermont, had developed a mutually respectful relationship throughout...