Even though Donald Trump is a flamboyant billionaire, many blue-collar voters embraced him as the presidential candidate who would lift them out of their economic rut. “I will bring jobs back and get wages up,” Mr. Trump said last summer, vowing to get tough on trade, Mexico and China.

But this Labor Day, his first while in office, it remains unclear whether Mr. Trump’s initiatives have done much to help workers, whether blue-collar or any other collar. It is clear, however, that he has taken several steps that will hurt workers, most notably his decisions to delay, weaken or erase Obama-era workplace regulations. For instance, his administration has postponed rules that protect workers from dangerous silica dust and beryllium.

Mr. Trump has repeatedly trumpeted actions he has taken to help workers. He has withdrawn from the 12-nation Trans-Pacific Partnership trade pact that he said would clobber American factory workers, he has moved to crack down on imported steel and aluminum, and he has boasted that coal mines are reopening and factories expanding thanks to him. In one of his proudest moments, he flew to Indianapolis to announce that he had persuaded the Carrier Corporation not to ship 1,100 factory jobs to Mexico.

Many of Mr. Trump’s moves to help workers have come with a serious downside. He has given green lights to the Keystone XL and Dakota Access pipelines, which will help create a few thousand construction jobs — although environmentalists protest that the pipelines will hasten global warming by increasing America’s reliance on fossil fuels. His threats to place tariffs on steel and aluminum imports might restore some jobs in those industries, but they could spur Chinese or European retaliation against other American industries, costing jobs. Moreover, any tariffs on steel and aluminum could harm industries — like automobiles and appliances — that use these metals, reducing employment there as well.