This is quoted from New York Times,
the article titled " Romney Appears the Ohio Winner ; Santorum Strong "
" But all eyes were on Ohio, which The Associated Press called for Mr.Romney early Wednesday morning, capping a turbulent night in which the result see-sawed both ways within a very tight range."
I can understand the general concept of this line ; Ohio was the key state in this nomination race so it took much of attention. And the result made Mr. Romney a winner but he could only pointed to the squeaker.
Q : The problem I have is , the use of which in front of Ohio. What does which refer to? If it refers to Ohio, whose objective is it?
I believe it would be correct to write Where rather than Which.