LIMA — US Secretary of State Hillary Rodham Clinton repeated on Tuesday her statement taking sole responsibility for security at all of America’s diplomatic missions, an attempt to clear a political obstacle for her boss, President Obama, ahead of his second debate with Republican Mitt Romney.

‘‘I take responsibility,’’ Clinton said in a written statement. ‘‘I’m in charge of the State Department’s 60,000-plus people all over the world [at] 275 posts.’’