U.S. and Iraq near a 'bridge' deal on status of U.S. troops

U.S. and Iraq near a 'bridge' deal on status of U.S. troops:

"BAGHDAD - By the end of July, US and Iraqi officials hope to finalize a deal
that would map out the role and length of stay for US troops in the country."

What ever the length of American troops in Iraq is, I think it cannot be a unilateral political decision made in Washington. That means McCain can't force the troops to remain, and Obama can't force the troops to leave. What is missing in much of the discussion is what do Iraqi's want, and I am not sure that is a simple item to answer.