The Obama administration's decision to sharply curtail immigration enforcement won't merely exacerbate the problem of unlawful border crossings. It also will intensify the difficulty of crafting a legislative solution to illegal immigration. And the feds have the gall to chide Arizona.

Last week, Sen. Lindsey Graham, R-S.C., and the six other Republican members of the Senate Judiciary Committee wrote Department of Homeland Security Secretary Janet Napolitano to express "growing concern about the Department of Homeland Security's execution of U.S. immigration laws."

They have good reason to worry. Many of the new "administrative" enforcement rules were issued this year after Arizona, rightly frustrated over the federal failure to control its border with Mexico, adopted a state law empowering police to ask for immigration documents when making a stop for other reasons.

The Justice Department sued Arizona to block the law in July and has issued a rule barring any law enforcement officer in the U.S. from using misdemeanor traffic stops to apprehend illegal aliens for deportation. Justice has also sued the Maricopa County (Ariz.) sheriff for alleged abusive enforcement of immigration laws and the Maricopa Community College District for asking job seekers to provide proof of legal residency.

In addition, the Immigration and Customs Enforcement agency has put new caps on enforcement agreements with many states and municipalities. Under those limits, the ICE will only deport illegal aliens convicted of serious felony offenses and release the others.

Three months ago, the union representing 7,000 ICE law enforcement officers voted "no confidence" in ICE director John Morton and his top assistant for pursuing amnesty over enforcement and for lax detention center policies. Undeterred, on Aug. 20 Mr. Morton directed that as many as 17,000 pending deportation cases should be evaluated for dismissal. Another branch of the Department of Homeland Security, Citizenship and Immigration Services, has described further "administrative alternatives to comprehensive immigration reform" that would "extend benefits and/or protections to many illegal aliens."

These changes raise the temptation to illegally enter our nation across the 2,000-mile border with Mexico -- and the risks faced by those who do. Last month, the worst related atrocity on record occurred when smugglers working with drug gangs murdered 58 Central American men and 14 women seeking to enter the U.S. after failing to extort more money or promises to be drug runners.

The Obama administration isn't just abdicating its duty with this continuing retreat from immigration enforcement. It is further polarizing the already-divisive national debate on the issue -- and undermining the chances of overdue immigration reform.