OUT in the savannah of American politics, the Democratic Party lacks big beasts. Republicans control the White House and Congress and, in the country at large, hold 33 governors’ mansions and almost as many state legislatures. Not since the 1920s have Democrats carried so little clout at the state and federal level. Just one Democratic pack moves with the swagger born of electoral success: big-city mayors. Democrats head 17 of the 20 largest cities, from New York to inland centres like Denver, a fast-growing, diverse spot at the foot of the Rockies, once known for cows, Coors beer and hydrocarbons, now abuzz with tech start-ups and millennials seeking jobs in finance and health care.

In a backhanded tribute to their power, President Donald Trump has prepared a trap for Democratic municipal leaders. It is built around immigration enforcement, and the reluctance of many urban leaders to work too closely with federal immigration authorities—notably the black-clad agents of Immigration and Customs Enforcement (ICE). One of Mr Trump’s first executive orders threatens to deny federal funds to so-called “sanctuary jurisdictions”, meaning local governments deemed to be shielding “removable aliens” from deportation. On March 20th, obeying that same executive order, ICE issued the first of what are to be weekly reports tallying rejected “detainer” requests. In plain language, the report lists each time that local city officials, police or prison officers declined to hold foreigners eligible for removal long enough for them to be picked up by federal agents.

Some mayors sound ready to jump into Mr Trump’s trap, eyes open, declaring that their fiefs are indeed “sanctuary cities”— thereby reinforcing the charge that Democrats are out of touch with regular folk who want safe communities. Marty Walsh of Boston has offered his City Hall office as a “safe space” for migrants fearing deportation. On the Democratic left, there is much talk of resistance. For Mr Trump—a man elected by the America of small towns, forgotten rustbelt cities and rural areas—such defiance is proof that big cities are sinks of dysfunction, run by liberal elites too craven or corrupt to enforce the rule of law. As a candidate Mr Trump brought the relatives of people killed by migrants to rallies. As president he accuses sanctuary cities of causing “immeasurable harm to the American people”.

Put more simply, partisans on left and right see an advantage in fear-mongering. In contrast Michael Hancock, the self-styled moderate Democrat who has been Denver’s mayor since 2011, believes that fear undermines good governance. The city’s second black mayor, his problem-solving prowess was hard-won. One of ten children, he was brought up by a single mother. At times the family endured homelessness and nights without supper. Mr Hancock, a serious youth, started a mentoring scheme while at a high school plagued by gangs. Two brothers served time in jail, one died of AIDS and a sister was murdered by her boyfriend. He made it to college after a gig as a mascot for the Denver Broncos.

Today, interviewed in Denver’s neoclassical civic centre, the mayor cuts a genial but earnest figure. He avoids the label “sanctuary city” and is adamant that Denver does not breach the terms of Mr Trump’s executive order. He is also adamant that the new president’s approach makes his city less safe. Since January, he notes, four domestic-violence cases collapsed after victims declined to testify, fearing detention by ICE agents seen staking out the municipal court. Denver, a city of about 700,000 people, is home to an estimated 55,000 undocumented immigrants, according to the Pew Research Centre, a think-tank. City prosecutors report a fall in calls reporting crimes to police in districts like Sun Valley, home to many Hondurans and other migrants.

Mr Hancock is to ask ICE to avoid detaining people inside courthouses, just as agents are currently meant to avoid arrests at schools, hospitals and churches. Yet Denver takes a more moderate line on working with the feds than cities like San Francisco, where in 2015 a serially deported felon was freed to kill after the then-sheriff ordered officers to avoid contacts with ICE. Denver’s position is more nuanced: the city notifies the feds when a serious offender is about to be released and honours ICE warrants. But when ICE simply asks for someone to be held past their release date, without a warrant, Denver declines. In part, that is because Denver believes so-called “detainers” are unconstitutional. In part, the city believes scarce resources should be focused on removing serious criminals. Mr Trump’s government wants to cast a broader net: in its March 20th report, ICE chides Denver for declining to hold a Mexican accused of drunk-driving.

Things to do in Denver

Some Republicans argue that America’s future lies in admitting highly skilled legal migrants while cracking down hard on illegal residents. Mr Hancock suggests, gently, that they misunderstand the global contest for talent and investment. Why would skilled foreigners choose a home that is harshly unwelcoming to other newcomers, he asks? “Nobody wants to live in fear,” he says, noting that recent chaotic travel bans have left some University of Denver students scared to travel home for spring break. It must be possible to strengthen immigration enforcement while being humane, he argues. “It doesn’t have to be either/or.”

Mr Hancock’s city is solidly Democratic; just 19% of its votes went to Mr Trump. But his job often involves policies affecting the wider Denver metro region. That requires coalition-building in Republican-voting suburbs and listening to the concerns of rural neighbours—including farmers who rely on immigrant labour.

Asked if the Democrats’ concentrated success in cities is itself a sort of trap, the mayor agrees. He urges Democrats to become “the metro party”. Politics, metro-style, requires appealing to moderates, liberals and even conservatives, he explains. For now, Mr Hancock is a big beast in municipal politics. If Democrats are smart, they will give him more room to roam.