BAGHDAD — Under intense U.S. pressure, Iraq's parliament approved a law Wednesday paving the way for the first provincial elections in four years following months of deadlock that American commanders warned could jeopardize the dramatic decline in violence. The breakthrough came after lawmakers decided to postpone a decision on how to resolve a power-sharing dispute over the oil-rich city of Kirkuk. The Kirkuk controversy has stoked ethnic tensions in northern Iraq and stalled approval of the election bill. U.S. officials hope the election, which must be held by Jan. 31 according to the new legislation, will give greater representation to minority Sunni Arabs. Many Sunnis and some Shiites boycotted the last provincial election, in January 2005, enabling Shiite religious parties and the Kurds to win a disproportionate share of the seats.