Visual spatial attention serves to select locations of interest in the visual field and enhances the cortical representation of objects at those locations. Previous studies suggest that neural activity in primate frontal eye fields (FEF) is involved in the spatial selection of salient stimuli in complex visual environments for eye movements and spatial attention. Here, we explore the origin of the spatial selection signal in FEF and its relationship to measures of covert spatial attention. We compare the timing of spatial selection for the location of the target in two simultaneously recorded cortical signals: local field potentials (LFPs) and spikes. LFPs are thought to represent synaptic input, while spiking activity is the output, of the area around the electrode tip. We found that spatial selectivity identifying the location of the target in the visual search appeared in the spikes about 30 ms before it appeared in the LFPs. This suggests that the spatial selection signal is computed locally in FEF from spatially non selective inputs. Additionally, we show that the magnitude of spatial selection in FEF is related to behavioral measures of attention during the time period in which the stimulus is being processed by the visual system. This relationship shows that FEF is directly involved in spatial attention.