Protesters chant during a May Day rally in downtown Los Angeles. The Los Angeles City Council voted in May to increase the minimum wage to $15 by 2020. (Sandy Huffaker/Getty Images)

It was a couple of days before Labor Day weekend, and the U.S. Chamber of Commerce had called a news briefing to go over labor policy developments on its radar for the fall. But before doing that, Senior Vice President Randel Johnson felt the need to play some defense.

First, he went over polling that indicates that most people feel positively about their employers, not in need of protection from them. “I think that’s good news, and I think this Labor Day we’ll see the unions dismiss that kind of data again,” Johnson said. He paused, and then went on, as if deciding to get some things off his chest.

“And I wouldn’t hammer on this so much,” Johnson said. “But there was a piece in The Post just this morning talking about a poll that came out about how unions are going up in the image of the public.”

The poll had found that approval ratings had risen to 58 percent among the general public and to 66 percent among adults under 35. Johnson argued that the poll had also found that only 37 percent of people said they wanted unions to have more power, which The Post columnist hadn’t mentioned (though that number has risen in recent years, too).

Finally, he moved on to a theme that has been spreading in liberal circles these days.

“I want to spend a little time on this notion, because it’s so ludicrous, that unions are a ticket to the middle class,” Johnson said, referring to a Labor Department blog post that argued that the decline of labor unions has played a role in the rise in inequality in America. Those two trends are purely correlations, Johnson said, no more related than his own investments in the stock market and its decline in the 1980s.

After a long period of not having to worry too much about unions, Johnson is in rebuttal mode, because the past couple of years have seen more victories for unions and workers generally than they have enjoyed in quite some time.

To briefly sum up, the troubling news for business comes from three main corners.

First, and top of mind for the Chamber of Commerce, is a string of National Labor Relations Board decisions that could start to turn the tide back in favor of unions after decades of slow going due in part to the fact that employers had learned to evade traditional forms of labor organizing.

Most notably, a new rule has streamlined election procedures, which gives employers less time to tell employees why they don’t think a union would be helpful. And just a few weeks ago, the board ruled that layers of subcontracting and franchising relationships won’t necessarily protect companies from having to bargain with the workers they control.

Second, President Obama has been using the full range of his executive powers to try to raise wage standards, with a series of executive orders requiring federal contractors to pay more, have records free of labor law violations and — as of today — offer employees paid sick leave. That affects only a few hundred thousand people, which is a small chunk of the workforce, but it could have the effect of setting a standard that states and municipalities try to meet.

And third, a union-led push for minimum wage hikes up to $15 an hour has propelled a spate of new laws in states and cities that will boost the income of the lowest-wage workers. Union cheerleading for those broadly popular measures may have had something to do with those recent poll numbers showing unions on the upswing in the eyes of the American public. And a series of labor victories at popular online news outlets — Gawker, Vice and the Guardian, among others — could help make unions more relevant to a generation that hasn’t understood them as a solution.

For those who are part of unions already, that membership has paid off. In the first half of a giant year for contract negotiations, Bloomberg BNA calculated that the weighted mean of first-year wage increases in settled contracts covering 440,000 workers was 4.3 percent, up from 2.9 percent last year.

To be sure, the year hasn’t been without setbacks for labor advocates. November’s elections, in which sworn union enemies such as Wisconsin Gov. Scott Walker (R) and Illinois Gov. Bruce Rauner (R) retained or gained power, still smart. After putting everything it had into the fight to defeat fast-track approval for a massive free-trade deal, the AFL-CIO narrowly lost. And there are still dangers on the horizon, including a Supreme Court case that could create a right-to-work law for public-sector workers nationwide.

But in some places, unions are beating back those political threats — including attempts to pass right-to-work laws in states such as Missouri and West Virginia. Though it’s still tough going in Southern states that went right-to-work long ago, several unions are still working hard to figure it out.

And at the moment, if the Chamber of Commerce’s Labor Day briefing is any indication, it’s enough to start making the business community nervous.