In reality, mayors alone wield limited control over crime rates. Several researchers could point to no studies suggesting that the partisanship of a mayor has an effect on this. And while homicides have spiked this year in big cities, they have risen by similar amounts in a number of smaller cities with Republican mayors, including Tulsa, Okla., and San Bernardino, Calif.
The president, however, has never mentioned these places — or Republican-led Miami, Jacksonville, Fla., or Fort Worth — in his vows to deploy federal forces to help control urban crime.
Numerous studies suggest that the partisanship of mayors has limited effect on much of anything: not just crime, but also tax policy, social policy and economic outcomes.
The researchers Justin de Benedictis-Kessner and Christopher Warshaw have found that Democratic mayors spend more than Republican mayors. “But the differences are pretty small,” said Mr. Warshaw, a political scientist at George Washington University. “They’re not enough to drive large differences in societal outcomes in things like crime rates.”
This is partly because mayors are constrained in their ability to execute ideological agendas. Cities can’t run deficits. States limit their authority to raise taxes and enact laws on many issues. And cities lack the power the federal government has to shape labor laws, or immigration policies that can affect their population growth.
The president has effectively ascribed a level of power to mayors that they simply do not have.
“The assumption is that cities are city-states,” said Joshua Sapotichne, a political scientist at Michigan State University. “What that means is that they have the autonomy to act on the preferences of their constituents. And that’s not even true with respect to social distancing, mask mandates and lockdowns on the Covid side.”
The president has harshly criticized Chicago for failing to control gun violence. But in the past the city took relatively severe policy responses, outlawing handguns and gun sales. Federal judges overturned those efforts, making clear again how constrained local officials are.