It won’t be any big challenge to get a new “sanctuary city” initiative on Tucson’s ballot this year.

All the organizers need to do is gather 9,241 valid signatures from city voters by July 5, which is highly doable.

But convincing Tucson voters that this is a necessary addition to the city charter? That will be a challenge. That’s because a new sanctuary law will mean a whole heap of trouble for Tucson in exchange for debatable gains.

The effort derives, of course, from the now-codified SB 1070, which requires Arizona police officers to question detainees about their immigration status if the officer develops reasonable suspicion that the person is in the country illegally. Much of the law was thrown out by the courts, but that part stayed in.

Since then, police departments have struggled with how to implement the law without profiling people. But the Tucson Police Department has been one of the more progressive agencies in limiting when officers may ask about immigration and when they may call federal authorities.

While trying to adhere to the state law, the department has, for example, prohibited officers from questioning juveniles about their immigration status without a parent, attorney or guardian present.

The City Council declared Tucson an immigrant-welcoming city in 2012, a designation without much practical meaning, and reinforced that with a new declaration after President Trump was elected in 2016.

So far, Tucson has stayed in that sweet spot where officers aren’t aggressively pursuing immigration questions and are trying to keep open communications with immigrant communities, but are also staying out of the crosshairs of the state Legislature.

“As a practical matter, we have done, I think, a pretty good job of keeping the trust of these vulnerable populations,” said TPD chief of staff and former legal counsel Mike Silva. “We’ll remain committed to that no matter what happens with this ballot initiative.”

But if the initiative passes, we are pretty much guaranteed a fight with the state, as Mike Rankin, Tucson’s city attorney, said in an opinion issued Wednesday.

For example, the initiative defines traffic stops as a situation in which it is not “practicable” to question a detainee if the vehicle is stopped by the side of the road. Rankin says that likely violates state law.

Inevitably, such a restriction would be challenged under the state law that allows individual legislators to pursue ordinances that they think conflict with state law. Violations of state law put a city’s state-shared revenue in jeopardy.

We can expect that such a challenge would happen not just on this particular aspect of the initiative, but others as well.

To the extent that the initiative survives a challenge, we should expect that the Legislature will attempt to pre-empt this city ordinance by outlawing it, then challenging it.

Billy Peard, the ACLU attorney who helped draft the initiative, tells me he did it carefully to avoid conflicting with SB 1070 while defining its demands as narrowly as possible.

“Tucson ought to be in the forefront of continuing to do what it can to limit the negative effects of SB 1070,” Peard said. “We’re going to come out of this with a clear, crisp legal model that can be used throughout the state.”

Maybe. Or maybe we’d be drawn into endless legal battles with the state government that ultimately give us not much more than we’ve already got.

New mayoral candidate

Tucson now has a mayoral candidate who is not a Democrat. Ed Ackerley, the co-owner of Ackerley Advertising, has confirmed he is jumping into the mayoral race.

The Tucson businessman will run as an independent, saying he will bring Tucsonans together to lead the city in a new direction that is “business-friendly and people-powered.”

“As a native Tucsonan involved in the community for decades and with extensive leadership experience, it is time for me to offer this expertise to the city,” he said.

Running as an independent is a double-edged sword — there is no primary for independents, but Ackerley will need several thousand signatures to get on the November ballot.

Ward 4 candidates

The race for Tucson City Council is starting to shape up in Ward 4. Democrat Nikki Lee, who lost a hard-fought primary for state Legislature last year, announced this week she plans to run for the southeast-side seat.

Lee lost in a four-way race for two seats in Legislative District 10 in the August primary.

While she is the only announced candidate, others are likely to join in and make it a primary, Pima County Democratic Chair Alison Jones told me.

On the Republican side, longtime Tucson Unified School District board member Michael Hicks is planning to run.

The ward leans Republican, but because of Tucson’s citywide general elections, in which all city voters choose each ward’s council member, Democrats often win.

Star reporter Joe Ferguson contributed to this column.

Contact: tsteller@tucson.com or 807-7789. On Twitter: @senyorreporter