This week the Senate held a hearing that highlighted the crimes committed by illegal immigrants that had avoided deportation because officials in self-declared “sanctuary cities” refused to hand them over or notify federal officials of their presence. The father of Kathryn Steinle, a young San Francisco woman who was murdered by an illegal immigrant who had been freed by city officials complying with its sanctuary rules, asked senators to support a bill defunding those municipalities that refuse to cooperate with immigration authorities. Yet what was interesting about the hearing is not so much the slim chances of the bill becoming law. Rather, it was the way Democrats and the liberal media did their best to ignore the issue. Listening to activists that view the focus on sanctuary cities as a thinly veiled effort to demonize immigrants, the political left is still convinced that the issue not only works to their advantage but also will help ensure victory in 2016. But their tone-deaf response to grieving parents like Jim Steinle betrays a flaw in their political strategy. If the debate shifts from foolish talk about “self-deportation” to reasonable efforts to enforce the law, immigration stops being about respecting Hispanic voters and starts becoming a liability for a party that is all in on amnesty for illegals.

Most Americans are sympathetic to immigrants and rightly despise nativist rhetoric. To the extent that Republicans become identified with anti-immigrant attitudes, it will not only hurt their ability to win the votes of Hispanics but also alienate many other voters. But the Steinle murder and similar crimes that were highlighted in the Senate hearing shifts the conversation away from prejudice and instead illustrates the problem of a policy stance that treats the law as a detail to be flouted at will.

Some Democrats grasp the inherent danger that sanctuary cities pose to their party. Senator Dianne Feinstein, who helped make San Francisco a sanctuary city during her term as mayor back in the 1980s, has put forward her own proposal on the issue. Her bill would not penalize cities with that designation but still would force them to cooperate with federal authorities. Yet even that seemingly anodyne proposal earned her furious denunciations from activist groups who oppose what they say is its “criminalization of immigrants.” But while the left profits from sympathetic illegals such as the so-called Dreamers who were brought here by their parents, the willingness to extend blanket amnesty even to lawbreakers reveals the danger for Democrats.

The problem is that if they are so in thrall to pro-illegal immigrants that they are prepared to defend the indefensible in the form of a sanctuary city policy that lets murderers walk, they will find themselves on the wrong side of a highly emotional issue. As much as responsible observers have denounced Donald Trump’s inflammatory rhetoric about Mexicans who come here illegally, it would be foolish for members of either party to assume that there is no cost to amnesty policies that, like sanctuary cities regulations, treats the law as something to be flouted with impunity. As I noted earlier in the month, Hillary Clinton’s open support for sanctuary cities may yet haunt her in 2016. Her assumption that there are no votes to be lost in the center on this issue may yet prove a colossal mistake.

Republicans still need to be careful on this issue. To the extent to which Donald Trump uses his celebrity to position himself as the loudest voice on the right about the issue, as he did when he announced his presidential candidacy with remarks about most Mexican illegals being rapists and drug dealers, they will find themselves marginalized. But if, as party leaders fervently hope, Trump is but a bad memory for the GOP next year, the ability of immigrant groups to force Democrats to stick with them on outrageous stands on sanctuary cities may prove a far greater problem for them than the reality star is for the Republicans.