Based on what?
State Department says born of US parents on foreign soil is a US citizen.
http://travel.state.gov/travel/cis_pa_tw/cis/cis_1753.html
...a child born in a foreign country to U.S. citizen parents may be both a U.S. citizen and a citizen of the country of birth.
Acquisition of U.S. Citizenship by a Child Born Abroad
http://travel.state.gov/law/citizenship/citizenship_5199.html
A child born abroad to two U.S. citizen parents acquires U.S. citizenship at birth under section 301(c) of the Immigration and Nationality Act (INA) provided that one of the parents had a residence in the United States or one of its outlying possessions prior to the childs birth. The child is considered to be born in wedlock if the child is the genetic issue of the married couple.
U.S. law is clear.
A child born to U.S. citizen parents abroad who make proper application for a consular birth certificate is as natural born as a child born to U.S. citizen parents in Omaha.