  Given a finite cover f:tilde{G} \to G and an embedding of tilde{G} in the
plane, Negami conjectures that G embeds in P^2. Negami proved this conjecture
for regular covers. In this paper we define two properties (Propserties V and
E), depending on the cover tilde{G} and its embedding into S^2, and generalize
Negami's result by showing: (1) If Properties V and E are fulfilled then G
embeds in P^2. (2) Regular covers always fulfill Properties V and E. We give an
example of an irregular cover fulfilling Properties V and E. Covers not
fulfilling Properties V and E are discussed as well.
