HÉNIN-BEAUMONT, France — The far-right National Front, under the new leadership of Marine Le Pen, is sending shivers through France’s political world in the maneuvering for the 2012 presidential elections. Ms. Le Pen, a more telegenic and less cheerfully divisive figure than her father, Jean-Marie Le Pen, is getting around 20 percent in early opinion polls, putting her about even with the main parties of the right and left.