Trump’s inroads in union ranks have labor leaders scrambling

Such sentiments help explain why Mr. Trump came as close among voters from union households as any Republican presidential candidate since 1984. And they are the basis for an approach espoused by his top political adviser, Stephen K. Bannon, who has mused about a tectonic political shift that would rearrange traditional partisan allegiances around economic interests.

Surely no small benefit of that realignment would be to divide organized labor, a key Democratic constituency, and the White House has been shrewd about capitalizing on workers’ pro-Trump sentiment.

Mr. Trump summoned the heads of the building and construction trade unions, most of which supported Mrs. Clinton, to discuss infrastructure spending three days after his inauguration. “It was a substantial meeting about good middle-class jobs,” said Terry O’Sullivan, general president of the Laborers’ International Union of North America, adding that Mr. Trump was the first president to invite him to the Oval Office.

Some of Mr. Trump’s other early moves, like his presidential memorandums giving the go-ahead to the Keystone XL and Dakota Access pipelines and killing the Trans-Pacific Partnership trade agreement, and his announcement that he would quickly seek to renegotiate the North American Free Trade Agreement, were clearly conceived with a similar objective.