Kyoto for nukes

For all the Democratic fussing over the Republican Senators' letter to Iran, they forget the Constitution.
A President can sign a treaty, but it's just a signature unless the Senate approves.
Like the Panama Canal treaty in the 1970s, you need the approval to give it full force of the government.
Democrats like to tout the Kyoto Treaty, but it went down in flames in the Senate.
A treaty without Senate approval is just a piece of paper.
Too bad if Democrats and President Obama don't understand that.