IMO, we lost the best opportunity for comprehensive immigration reform in 2007. It had bi-partisan support, including Bush.
Then McCain backed away from his own Kennedy-McCain
Comprehensive Immigration Reform Act of 2007 to run for president and felt a need to pander to the conservative wing of his own party to get the nomination.
We could probably have a comprehensive bill this year if only a handful of Republicans would agree to a process of providing a pathway to citizenship for most (not all) of the illegals already here.