Question: Given the following passage  "In October 2013, the New York Post reported that Schwarzenegger was exploring a future run for president. The former California governor would face a constitutional hurdle; Article II, Section I, Clause V nominally prevents individuals who are not natural-born citizens of the United States from assuming the office. He has reportedly been lobbying legislators about a possible constitutional change, or filing a legal challenge to the provision. Columbia University law professor Michael Dorf observed that Schwarzenegger's possible lawsuit could ultimately win him the right to run for the office, noting, "The law is very clear, but it’s not 100 percent clear that the courts would enforce that law rather than leave it to the political process."",  answer the following question. Note that the answer is present within the text.  Question: What was a primary issue?
Answer:
a constitutional hurdle