Tucson’s upcoming ballot measure to become Arizona’s first “sanctuary city” underscores just how important it is to have President Trump in the White House fighting for a lawful immigration system.

Arizona has done more than any state in the country to counter the efforts of open borders activists to halt the enforcement of immigration laws. Even as we face the prospect of our second-largest city refusing to cooperate with federal law enforcement, the state government has made it clear we will sue Tucson or enact additional anti-“sanctuary” laws if the ballot measure passes.

Unfortunately, even the threat of state action is not enough to discourage liberal groups from trying to tie the hands of law enforcement and prevent lawful deportations. Action at the federal level is needed, and that’s why the Trump administration’s recent progress on this front is so important.

In 2010, alarmed by the rapid spread — in neighboring California and elsewhere — of policies specifically designed to prevent local law enforcement and government officials from cooperating with federal immigration enforcement, Arizonans took a stand. I signed into law a wide-ranging set of policies designed to combat illegal immigration and restore the rule of law.

In 2012, open-borders groups successfully argued before the U.S. Supreme Court that certain sections of that law, SB 1070, were unconstitutional because immigration enforcement is the sole purview of the federal government. I, along with many legal scholars from around the country, was disappointed with much of the court’s ruling. Still, critical elements of the law, including the admonition that “no official or agency of this state or a county, city, town, or other political subdivision of this state may adopt a policy that limits or restricts the enforcement of federal immigration laws to less than the full extent permitted by federal law,” remained intact.

The proponents of Tucson’s Proposition 205, however, want to disregard our laws and enact what is possibly the most sweeping sanctuary policy in the country. The initiative would prohibit police from engaging in any meaningful cooperation, not just with federal immigration authorities, but with federal law enforcement of any kind. It even refers to working with federal law enforcement as “collaboration,” as if our federal agents were an unlawful, occupying force in Arizona.

The activists who objected to SB 1070 were never truly concerned about reserving the power to regulate immigration for the federal government. They were simply interested in preventing the enforcement of immigration laws by anyone and creating a de facto right for undocumented immigrants to reside in Arizona. The text of Tucson’s ballot initiative spells out the same goal, stating that “It is the policy of the city that the city be a sanctuary and safe refuge for all persons, regardless of ... immigration status.”

Arizonans are doing what they can to stop this lawless proposal in its tracks. Tucson’s own Democratic mayor has come out against the measure, and numerous local groups are trying to combat the false narrative that this initiative is merely about love and kindness.

That sort of civic engagement is necessary, but there also must be clear consequences. An Arizona law that is already on the books will withhold over $100 million of state funding if the Tucson city government starts working against immigration enforcement, yet that might not be a sufficient deterrent.

That’s why it’s so important that we have the backing of a White House committed to enforcing the law. President Trump’s Justice Department has fought to use existing federal law to prohibit sanctuary cities from receiving millions of dollars in law enforcement grant money intended for cities that enforce the law. Tucson stands to lose up to $12 million in additional federal funds if voters approve the sanctuary initiative.

Many of the same pro-undocumented immigrant groups that fought against SB 1070 have also tried to stop the Trump Justice Department from withholding those grants. Luckily, even the notoriously left-leaning U.S. Court of Appeals for the 9th Circuit recently refused to shield sanctuary cities from the consequences of their refusal to cooperate with federal law enforcement.

I’m confident that the voters of Tucson will not be fooled into passing this outrageous ballot measure, but the fact that open-borders activists are pushing the idea now — even in a state such as Arizona that has made clear time and again that we do not want California-style undocumented immigration “sanctuaries” — shows that we need all the help we can get. Arizona lawmakers are ready to do their part, and should that become necessary, they’ll be able to count on the support of a committed ally in the White House in President Trump.

Jan Brewer is the former governor of Arizona.