Obama has systematically dismantled immigration laws
One of the Left's loud complaints about deporting illegals was that the government wasn't acting against U.S. business that hired illegals. "Go after the businessmen," they said. Accordingly, someone devised a computerized list--called E-Verify--that businesses could use to determine whether someone was could legally work in the U.S. It worked quite well, even though it was never mandatory.
Suddenly faced with an effective deterrent to illegal job-seekers (something they didn't actually want), the administration refused to consider making the use of E-Verify mandatory for all employers, and resisted efforts to permanently reauthorize it.
Next the Obama regime targeted programs that helped local law enforcement identify illegal aliens. Both the 287(g) and the Secure Communities agreements were rewritten so that illegal aliens wouldn't be deported unless they were guilty of some separate, "serious" crime. In effect, it was “don’t ask, don’t tell” for all other illegal aliens.