It has been open season on Michael R. Bloomberg’s record since the billionaire businessman broke from the pack of Democratic presidential candidates and won a place in Wednesday’s Democratic debate. Here’s a new area of concern: His record on Social Security.

Advocates for the program are expressing concern that Bloomberg has failed to utter the foursquare support for Social Security that’s a litmus test for Democrats, much less support for extending and expanding the program, as Elizabeth Warren and other candidates have advocated.

It’s true that Bloomberg’s rhetorical record on Social Security is alarming. His campaign plank on retirement security, released Sunday, has several positive elements — but some disquieting verbiage, too. And it may not be enough to erase his past attacks on the program.

Of all the Democrats in the race, “Michael Bloomberg is the worst choice to debate Donald Trump on an overwhelmingly important issue: Social Security’s future,” Nancy J. Altman and Linda Benesch of the advocacy group Social Security Works observed in an op-ed Tuesday. “Bloomberg’s position on Social Security is to the right of Trump’s stated position — and widely out of step with even Republican voters, let alone Democrats.”

They charge that Bloomberg “hasn’t changed his views” about the program, which over time have included supporting an increase in the retirement age and cutting back on benefit increases. “He’s just gotten smarter about hiding them.”

His position on Social Security may be an especially vulnerable spot for Bloomberg among Democrats. Let’s take a look.

First, the good things in Bloomberg’s platform, as of Sunday. He advocates applying a cost-of-living index for annual inflation that better reflects the living costs of seniors than the standard consumer price index used now. He’s talking about the CPI-E, which is also supported by most Social Security advocates, because it takes better account of housing and medical inflation.

Bloomberg also says he’d “examine options” for improving benefits for surviving spouses and family caregivers, who are shortchanged in the calculations of their lifetime earnings used to set benefits. Both shortcomings disproportionately affect women. But he doesn’t offer any details.

He does offer support for several other initiatives that would clamp down on predatory practices aimed at seniors and low-income households. He would restore some initiatives Trump has rolled back, such as the fiduciary rule binding brokers and insurance agents to put their clients’ interests first, raise the federal minimum wage to $15 an hour by 2025 and expand the earned income tax credit.

What unnerves Altman and Benesch is “what he doesn’t say.” More precisely, his use of weasel words to conceal his intentions. Bloomberg’s platform states, for example, that he’d “consider options for preserving and strengthening Social Security’s long-term finances.”

That’s phraseology, they assert, “frequently used by billionaire elites like Bloomberg as code for ‘cut Social Security to save it.’ ”

It’s also a bit unnerving that Bloomberg stresses “maintaining and enhancing benefits for the neediest recipients.”

Upgrading minimum benefits is part of most progressive proposals for expanding Social Security, but typically in the context of increasing benefits for everyone. The latter idea is what’s missing in Bloomberg’s plan. And that raises the specter of making Social Security more of a means-tested program, which is a formula for undermining its popular support.

Bloomberg’s past remarks about Social Security generate the most concern among progressives. In 2011, when he was mayor of New York, he compared the program to a “Ponzi scheme.” He tried to cover the remark with a joke, but the program’s advocates were listening.

The remark came during an interview with Time magazine. Asked how the notorious conman Bernard Madoff got away with scam for so long, Bloomberg said, “Everybody just thought, where did Madoff get the idea? A cynic would say Social Security. I would never say that. But it’s exactly the same thing, isn’t it?”

No. It’s nothing of the kind.

That same year, he explicitly supported the so-called Simpson-Bowles Commission’s recommendations on deficit reduction, which included reducing Social Security benefits.

In a 2012 op-ed in the Wall Street Journal, Bloomberg again called for enactment of the commission’s recommendations, among them “slowing the growth of entitlement costs including Social Security.” The thrust of his essay was to decry the “class warfare” that was then exemplified by the Occupy Wall Street campaign against the 1 percent.

A few words about Simpson-Bowles are appropriate here. Its recommendations on Social Security and Medicare were based on gross misrepresentations of those programs, spread most enthusiastically by Alan Simpson, a former Republican senator from Wyoming.

After serving on the commission, Simpson went on a nationwide tear, claiming that the program was never designed as a “retirement system” and that the original bill’s drafters deliberately set the retirement age at 65 because life expectancy in 1935, at the time of enactment, was 63. In other words, Simpson said it was designed from inception as a rip-off, which is egregiously wrong. (In fact, average life expectancy at the time was higher than 66 for everyone except newborns.) He larded his response to critics, even elderly retirees, with vitriolic and vulgar invective.

He challenged me to “find the word ‘retirement’ in your vast research, either uttered by Labor Secretary Frances Perkins or Edwin Witte, head of the Committee on Economic Security, appointed by President Roosevelt in 1934.”

I cited chapter and verse from the Congressional hearings on Social Security in 1935 and referred Simpson to the official record, which still can be found online.

In short, the Simpson-Bowles recommendations were not a star for Bloomberg to hitch his wagon to. They went nowhere in Congress.

If Bloomberg wishes to establish himself as a Democratic alternative to Donald Trump, he has to come clean on Social Security. Altman and Benesch say, “To get right on Social Security, Bloomberg must repudiate his past support for cuts (and) pledge that he will never support cutting a single penny of current or future benefits. Unless that happens, supporters of Social Security should consider him an enemy of the program.”

That would certainly set him apart from Trump, who has signaled that he’s open to Social Security cuts and whose latest budget proposal shreds Social Security, Medicare and Medicaid, the nation’s keystone social safety net programs. Now is his chance.

Pulitzer Prize-winning journalist Michael Hiltzik is a business columnist for the Los Angeles Times.