New York City Mayor Bill de Blasio unveils the “Progressive Agenda to Combat Income Inequality” at the U.S. Capitol on May 12. (Andrew Harrer/Bloomberg)

By honchoing a liberal “Contract with America” to combat income inequality, New York City Mayor Bill de Blasio is doing what so many of his predecessors have done: Use their bully pulpit in the media capital of the world and the nation’s largest city to champion an issue or raise their profile. Usually it’s both. But hizzoner would do well to remember a rock-solid rule of U.S. politics: Big Apple mayors never go beyond the confines of City Hall.

That’s not to say that what de Blasio advocates is unworthy of attention or implementation. Raising the minimum wage, universal pre-K, paid family and sick leave, and a series of ideas on closing tax loopholes that favor the super-rich; all would help instill fairness in our economy. Using his perch to champion these issues gives de Blasio and the issues serious consideration. The issues also give the mayor a voice in the Democratic Party at a time when the left wing is flexing its muscle trying to scuttle trade deals and put the fear of God into prospective presidential nominees (cough, Hillary).

Still, the wanderlust of a New York City mayor is never rewarded.

Democrat-turned-Republican-turned-Independent Mike Bloomberg (2002-2013) looked into running for president as an independent in 2008. The multibillionaire decided against it. There was no possible way he could win as an independent, even with a self-funded campaign. Republican Rudy Giuliani (1994-2001) tried a few times. There was that ill-fated run for the Senate in 2000 and the lackluster attempt at winning the 2008 Republican presidential nomination. Neither his record taming an ungovernable city or his stature as “America’s mayor” was enough to convince anyone to make him the national standard bearer of the GOP. Democrat Ed Koch (1978-1989) tried to make a break for Albany by seeking his party’s 1982 nomination for New York governor. He was beaten by then-Lt. Gov. Mario Cuomo. Republican John Lindsay (1966-1973) switched to Democrat in 1971 to seek that party’s presidential nomination. Like Giuliani, Lindsay dropped out after losing the Florida and Wisconsin primaries the following year.

With an approval rating resting at 44 percent, the lowest of his mayoralty, De Blasio is in no real position to cast a gaze beyond the city’s five boroughs. That 46 percent believe his nation-trotting is “distracting him from his duties as mayor” means the foundation of his progressive pedestal is wobbly. Nonetheless, de Blasio should keep using his Big Apple bullhorn to ensure the issues he cares about remain a part of the national conversation. And he will be more successful if he does what Harry Siegel of the New York Daily News says he must:”live up to his promise here.” Siegel writes, “To prove a progressive Democrat can govern more equitably for New Yorkers who felt priced out of Bloomberg’s ‘luxury city,’ without killing the golden goose.”

That’s a tall order.

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