et al. (2011b) consistent with the $\gamma$-ray blazar nature of the [[*WISE*]{}]{} candidates proposed in our analysis.

Summary and Conclusions {#sec:summary}
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Recently, we discovered that blazars have peculiar mid-IR colors with respect to other galactic sources or different classes of AGNs. In particular, we found that within the 3-dimensional IR parameter space they delineate a distinct, well-defined, region known as [[*WISE*]{}]{} Blazar Strip (Paper I). Moreover, this distinction, mostly due to the non-thermal emission that dominates the IR radiation of blazars, appears to be more evident when considering those blazars selected on the basis of their $\gamma$-ray properties (Paper II) so defining the [[*WISE*]{}]{} Gamma-ray blazar Strip ([[*WGS*]{}]{}). Then, in Paper III, we built the [[*WGS*]{}]{} parametrization to test the consistency of the low energy counterpart of the AGUs, associated in 2FGL with the [[*WGS*]{}]{}.

On the basis of these results, in the present work, we developed a new association method to search for blazar counterparts of $\gamma$-ray sources and we applied this method to the blazars of the 2FGL sample. We also provide new $\gamma$-ray blazar candidates, potential counterparts of the UGSs, that lie within their $\gamma$-ray positional error region, having the same mid-IR colors as the $\gamma$-ray 