We are happy that Mayor de Blasio has decided to run for president. It never hurts to have more New Yorkers in the race, if only to force the rest of the nation to confront its bias against the urban quality-of-life issues we cover every day at Streetsblog.

But as the mayor makes his case to the nation be the 46th president, he must resign, for the good of his current constituents.

For too long, the preparations for the presidential run have seized de Blasio’s attention on so many initiatives. We are concerned that vital work, even on the mayor’s once-cherished initiatives such as Vision Zero, will simply be shelved as the mayor galavants around the nation, as if caucus-goers in Brooklyn, Iowa, are going to care if de Blasio builds out the bike network in Brooklyn, N.Y.

There’s plenty of evidence that work is already being slow-walked:

• A redesign of Amsterdam Avenue, once a de Blasio priority, languished for over two years because the mayor didn’t get personally engaged amid community board obstruction.
• The fourth phase of the Queens Boulevard redesign — literally de Blasio’s signature street-safety project — has been stalled for over a year. There’s no timetable.
• Central Park West, where Australian tourist Madison Lyden was killed by a truck driver, still doesn’t have a protected bike lane.
• Congestion pricing passed as a vague measure by the state earlier this year, with the details of how it will be implemented put off. It’s already being watered-down with exemptions, putting it — and the revenue for the transit system that it was created to generate — at risk.
• Multiple community groups have called for the city to close just a few streets to car drivers — an initiative that needs mayoral approval. Other world capitals – London, Paris, Madrid, etc. — have improved quality of life by closing small parts of their central business district to cars. This mayor can’t be bothered to even consider it.
• De Blasio has not even been involved in a battle to save his own administration’s plan for a single playstreet in Jackson Heights, which a car dealership destroyed by exercising overlooked property rights at the last minute.
• He told us more than a month ago that he intended to take action against recklessly driving cops — but nothing has been done.
• State officials are working on a way to help food delivery workers do their jobs legally. De Blasio’s only contribution to that effort has been to arrest the low-wage workers. He needs to be part of the solution.
• We can’t even get an answer from City Hall about what kind of lines it plans to paint on Dyckman Street, where the city removed a set of protected bike lanes in August (!) and has left the wide roadway completely devoid of lane markings since.

Government insiders tell us it has become increasingly difficult to get the mayor to sign off on these and other initiatives — or create new ones — during this period when de Blasio has been getting ready to announce. On Wednesday night, Council Speaker Corey Johnson was asked about de Blasio’s increasing lack of leadership on Vision Zero and said he thought the mayor was fighting old battles and not moving ahead aggressively.

“I’m not sure that he has embraced that the conversation has moved on,” Johnson said.

That conversation will continue from now until the mayor’s certain defeat in Iowa next February — that’s more than eight months — without the mayor himself. Reminder: this comes as New York is in the middle of a 21-percent uptick in road deaths this year versus the same period last year. A cyclist who died this week in Crown Heights was the 10th bicycle rider to die this year — matching the total for all of last year.

The mayoralty of New York City is often said to be the second most important job in the country. It needs someone in the west wing of City Hall who shows up to work every day (perhaps even after a gym workout) with 100 percent focus on the lives of his fellow New Yorkers.

The mayor, of course, has a choice: He could resign to fully focus on his presidential ambitions, putting Public Advocate Jumaane Williams in charge of city government. Williams, at the very least, has no other job, so his focus would be entirely on running the city.

Or the mayor could remain in office, but empower his talented commissioners and deputies to do whatever it takes to get the job done — explicitly instructing them to take action to improve the lives of New Yorkers, without having to wait for a mayor who has his attention on every other town except this one. We trust DOT Commissioner Polly Trottenberg to do the right thing — so it has been frustrating to watch her stymied by her boss’s limited focus.

So go out there and get ’em, Mr. Mayor — but step aside and let someone else run the city.