Why do both Obama’s State Department and the Senate require two US citizen parents for those born abroad to attain natural born citizen status?

6/24/2009:

Why does the Obama State Department’s continued publication of the Foreign Affairs manual acknowledge that the issue requires two US citizen parents?

Why do both Obama’s State Department and the Senate require two US citizen parents for those born abroad to attain natural born citizen status?

AND WHAT ABOUT TED CRUZ AND MARCO RUBIO AS SENATORS???