We demand that the Obama administration, which is tasked with representing and implementing the wishes of the American people, submit any potential nuclear deal with Iran to the US Congress for approval.
The US Constitution requires that the US Senate approve any treaty with a foreign nation precisely because one person alone, even the President, should not be able to forever bind the United States in the face of the wishes of the American people and the Congress.
It's a matter of national security of utmost importance which will affect all Americans and their country for years and possibly decades to come, and they should all have a say in it.