Americans today face a profound challenge to preserve our common values and national promise.

Wage stagnation at home and our declining influence abroad have left Americans angry and frustrated. And yet Washington, D.C., offers nothing but gridlock and partisan finger-pointing.

Worse, the current presidential candidates are offering scapegoats instead of solutions, and they are promising results that they can’t possibly deliver. Rather than explaining how they will break the fever of partisanship that is crippling Washington, they are doubling down on dysfunction.

Over the course of American history, both parties have tended to nominate presidential candidates who stay close to and build from the center. But that tradition may be breaking down. Extremism is on the march, and unless we stop it, our problems at home and abroad will grow worse.

Many Americans are understandably dismayed by this, and I share their concerns. The leading Democratic candidates have attacked policies that spurred growth and opportunity under President Bill Clinton — support for trade, charter schools, deficit reduction and the financial sector. Meanwhile, the leading Republican candidates have attacked policies that spurred growth and opportunity under President Ronald Reagan, including immigration reform, compromise on taxes and entitlement reform, and support for bipartisan budgets. Both presidents were problem-solvers, not ideological purists. And both moved the country forward in important ways.

Over the last several months, many Americans have urged me to run for president as an independent, and some who don’t like the current candidates have said it is my patriotic duty to do so. I appreciate their appeals, and I have given the question serious consideration. The deadline to answer it is now, because of ballot access requirements.

My parents taught me about the importance of giving back, and public service has been an important part of my life. After 12 years as mayor of New York City, I know the personal sacrifices that campaigns and elected office require, and I would gladly make them again in order to help the country I love.

I’ve always been drawn to impossible challenges, and none today is greater or more important than ending the partisan war in Washington and making government work for the American people — not lobbyists and campaign donors. Bringing about this change will require electing leaders who are more focused on getting results than winning re-election, who have experience building small businesses and creating jobs, who know how to balance budgets and manage large organizations, who aren’t beholden to special interests — and who are honest with the public at every turn. I’m flattered that some think I could provide this kind of leadership.

But when I look at the data, it’s clear to me that if I entered the race, I could not win. I believe I could win a number of diverse states — but not enough to win the 270 Electoral College votes necessary to win the presidency.

In a three-way race, it’s unlikely any candidate would win a majority of electoral votes, and then the power to choose the president would be taken out of the hands of the American people and thrown to Congress. The fact is, even if I were to receive the most popular votes and the most electoral votes, victory would be highly unlikely, because most members of Congress would vote for their party’s nominee. Party loyalists in Congress — not the American people or the Electoral College — would determine the next president.

As the race stands now, with Republicans in charge of both Houses, there is a good chance that my candidacy could lead to the election of Donald Trump or Sen. Ted Cruz. That is not a risk I can take in good conscience.

I have known Mr. Trump casually for many years, and we have always been on friendly terms. I even agreed to appear on “The Apprentice” — twice. But he has run the most divisive and demagogic presidential campaign I can remember, preying on people’s prejudices and fears. Abraham Lincoln, the father of the Republican Party, appealed to our “better angels.” Trump appeals to our worst impulses.

Threatening to bar foreign Muslims from entering the country is a direct assault on two of the core values that gave rise to our nation: religious tolerance and the separation of church and state. Attacking and promising to deport millions of Mexicans, feigning ignorance of white supremacists, and threatening China and Japan with a trade war are all dangerously wrong, too. These moves would divide us at home and compromise our moral leadership around the world. The end result would be to embolden our enemies, threaten the security of our allies, and put our own men and women in uniform at greater risk.

Sen. Cruz’s pandering on immigration may lack Trump’s rhetorical excess, but it is no less extreme. His refusal to oppose banning foreigners based on their religion may be less bombastic than Trump’s position, but it is no less divisive.

We cannot “make America great again” by turning our backs on the values that made us the world’s greatest nation in the first place. I love our country too much to play a role in electing a candidate who would weaken our unity and darken our future — and so I will not enter the race for president of the United States.

However, nor will I stay silent about the threat that partisan extremism poses to our nation. I am not ready to endorse any candidate, but I will continue urging all voters to reject divisive appeals and demanding that candidates offer intelligent, specific and realistic ideas for bridging divides, solving problems, and giving us the honest and capable government we deserve.

For most Americans, citizenship requires little more than paying taxes. But many have given their lives to defend our nation — and all of us have an obligation as voters to stand up on behalf of ideas and principles that, as Lincoln said, represent “the last best hope of earth.” I hope and pray I’m doing that.

(c) 2016, Bloomberg · Michael R. Bloomberg