If William Thompson thinks he can gain ground in his run for mayor by playing politics with the pensions of city employees, our guess is that he’s going to get a rude awakening. Politics is what he was playing with his letter to ExxonMobil asking the oil company to investigate possible price gouging and complaining about executive compensation. He was joining the demagoguery over oil prices at the expense of a company that has recently been fueling high returns at the city pension funds over which Mr. Thompson presides and which hold $1.2 billion in ExxonMobil shares.

The comptroller is trying to spin this as an effort to preserve the value of that investment. Quoth he: “I am concerned that the growing perception of unfair windfall profits and egregious executive pay could strengthen the maelstrom of public outrage, pose significant long-term risks to the company’s reputation, and negatively affect consumer preference at gas stations around the country.”

The next thing you know, he’s going to try to sell the Brooklyn Bridge. In fact his letter to ExxonMobil fans the flames of public “outrage.” If he were truly concerned about risks to the company’s reputation, he would be out there reminding New Yorkers that high oil profits benefit millions of shareholders, including the city’s pension funds, and he’d be writing members of Congress asking them to tone down their anti-oil rhetoric. Instead of doing his part to shore up the reputation of the company his fund owns, Mr. Thompson seeks to sully that reputation.

His letter is but the latest in a string of efforts to leverage the city’s retirement plan muscle into a force for the far-left version of social responsibility at the expense of the capitalistic version of social responsibility known as shareholder value. He is not alone in this type of abuse. The state’s comptroller, Alan Hevesi, has thus far been mute on the question of big oil investments, but he has a history of using the state’s pension fund, of which he is the sole trustee, in an effort to play politics. His official Web site is peppered with press releases trumpeting the Common Retirement Fund’s new investments in New York companies, complete with estimates of the number of jobs those investments will yield. Beyond the Empire State, the California Public Employees Retirement System, or CalPERS, is notorious as a politically motivated investor.

If Mr. Thompson were a private investment advisor, his clients could sort it all out in the market. “Socially responsible” funds are growing increasingly common, and investors, from environmentalists to Catholics, now have the option of investing in mutual funds that will respect the dictates of investors’ consciences. But workers covered by the city pension plan can’t shop around for a manager. The comptroller is egged on by the president of the United Federation of Teachers, Randi Weingarten, whose members are covered by one of the city plans and who told the Sun’s Jill Gardiner last week, “the pension funds have to be invested in fiscally sound ways, but there is also a social responsibility here.”

The problem with socially invested city retirement funds, however, is that they make taxpayers prisoners of the comptroller’s conscience. Unlike private retirement accounts, New York’s public employee pensions are constitutionally protected. If the pension funds’ investments don’t work out, the taxpayers will have to make up the difference. This frees comptrollers like Mr. Thompson to send letters to big oil companies bemoaning big profits without having to worry about the consequences. The voters aren’t dumb – nor are the taxpayers – and as Mr. Thompson works on his mayoral campaign we’ll see what these sorts of shenanigans get him.