One of the nation’s largest labor groups embraced Donald Trump at the start of his presidency, in hopes he would create construction jobs and retreat from proposals that might reduce workers’ wages. But now the two sides are on the brink of war, endangering a key bloc of Trump’s support in Midwestern swing states in 2020. At issue is a deal gone bad between Trump and North America’s Building Trades Unions over a Labor Department apprenticeship initiative, the politics of which have grown more complicated since last month’s ouster of Secretary Alexander Acosta. Leaders of the union federation worry that the final version will undermine their own job-training programs and create a supply of cheap labor for developers, undercutting high-skilled construction workers who rely on prevailing-wage jobs to make ends meet. “It’s an existential threat to the Building Trades,” said a former administration official with knowledge of the discussions. And it has the powerful group — a union federation that represents millions of construction workers across the U.S. — seeing early signs of a member-driven revolt against Trump in 2020. Such a turn could further weaken Trump’s already-declining support in the Midwestern states that won him the presidency in 2016, when many Building Trades members embraced his pledge to create working-class jobs and improve the nation’s infrastructure. “The Building Trades have the potential to be a significant force in the 2020 election,” said Steve Rosenthal, a strategist and former political director for the AFL-CIO, “particularly in some of the key swing states like Michigan, Wisconsin, Pennsylvania and Iowa. "The Building Trades know how to mobilize their members and move votes,” he added. “And their opposition to Trump can have a ripple effect beyond their members and their families to other voters in the communities where their members live and work.”Play Vid Trump sought to shore up support with the Building Trades this week at an appearance in Pennsylvania. An instruction sheet given to workers attending the event said the president hoped to “promote good will from the labor unions,” and he wasted no time doing so. “I love the unions and I love the workers,” Trump said. “And, you know, when I built buildings in New York … I built them exclusively with unions. People don't understand that. I was exclusive.” (Until recently, it was virtually impossible for anyone to build anything in New York City without union labor.) Though its leadership endorsed Hillary Clinton in the 2016 campaign, NABTU has always been viewed as more conservative than other labor groups, and since Trump's victory it has weathered criticism from the left for that reason. Trump — who won the majority of white male union members — made a point of meeting with the leaders of several construction unions on his third day in office, after which NABTU President Sean McGarvey exalted their “common bond with the president.” “We come from the same industry,” McGarvey told The New York Times after the meeting. “He understands the value of driving development, moving people to the middle class.” In April 2017, McGarvey praised Trump as “the very definition of an American success story” before an audience of members in Washington. McGarvey’s group had a keen interest at the time in securing construction jobs from the Trump administration’s proposed $2 trillion infrastructure program, which never came to fruition. McGarvey also had an interest in dissuading Trump from an early impulse to push repeal of the 1931 Davis-Bacon Act, which requires the federal government to pay prevailing wage — typically union scale — on construction projects. Trump backed off the idea after floating it early in his presidency. But the Building Trades and the administration are increasingly at odds over the apprenticeship initiative, a proposed rule that would create industry-supervised job trainingprograms. The Labor Department’s proposal has received more than 160,000 comments, the vast majority of them from union members vouching for the strength of the unions’ existing training programs. Most of the comments implicitly rebuke officials in the White House who have sought to make the proposal less favorable to unions. The two sides appeared more in agreement in June 2017, when Trump issued an executive order aimed at “easing the regulatory burden” on apprenticeships. In an effort to expand job training to new industries, the administration proposed to create a class of “industry-recognized” programs with fewer restrictions than existing government-sanctioned programs. McGarvey agreed at the time to join Trump’s committee to help create the apprenticeship system — with the understanding that NABTU’s own government-supervised apprenticeships would be untouched, according to his chief of staff, Michael Monroe. NABTU says it had a deal with the administration to exclude construction jobs from the new proposal, to protect the Building Trades' existing programs for training pipe fitters, iron workers and roofers, among others. But that agreement was with Acosta. Now NABTU's leaders fear that White House acting chief of staff Mick Mulvaney and his deregulation hawks won’t honor the bargain. Trust between the Building Trades and the White House began to unravel in May, when the White House forced out Acosta’s chief of staff, Nick Geale, after an inquiry raised questions about his treatment of subordinates. But there was perhaps a deeper source of tension: Mulvaney and some domestic policy advisers judged Acosta too cautious on deregulation and too accommodating to unions. When he took over as acting chief of staff in January, Mulvaney had judged the situation so dire that he seized Acosta’s rulemaking authority, commanding final say on policy matters.Then came the Labor secretary’s resignation in July, days after Mulvaney urged Trump to fire him over a lenient 2008 plea deal that Acosta, then the U.S. attorney for southern Florida, had struck with wealthy sex offender Jeffrey Epstein. Before he left, Acosta persuaded Ivanka Trump, who was involved in the apprenticeship rulemaking, to keep construction out of the new industry-led program, according to the former administration official. The Building Trades had told Acosta that letting developers pay industry-recognized apprentices less than prevailing wage would create price competition with NABTU’s program. “It would lower standards, it would put workers at risk, it would put projects at risk, it would put communities at risk,” Monroe said. “All the features that make ours successful, to undermine that is to undermine the veracity of the system at large.” Acosta’s decision was also driven by politics, according to the former official, who noted the Building Trades’ strong grassroots operation in the Midwest. Democrats on Capitol Hill were sounding alarms about the Labor Department’s new industry-led program, too, warning that it risked creating low-quality programs with lax oversight. Acosta and three White House officials did not respond to requests for comment. In the proposed rule published in June, the Labor Department said it would not “initially” accept industry-led apprenticeship applications for the construction sector, but didn’t rule out doing so later. That language stirred deep anxiety among Building Trades leaders, and prompted NABTU to direct a torrent of public comments to the Labor Department about the proposal. NABTU leaders say they’ve observed a high volume of comments from the Midwest. An iron worker from Indiana, encapsulating the sentiment, told the Labor Department that his union apprenticeship provided a pathway to the middle class — and expressed concern that it would “disappear” under the administration’s proposal. In April, meanwhile, McGarvey said the Building Trades might not endorse any candidate 2020. Hacked emails released by WikiLeaks showed internal dissent from some member unions, including the Teamsters and the International Brotherhood of Boilermakers, following the federation’s endorsement of Clinton — demonstrating how tenuous NABTU support was for any candidate. Clinton performed poorly in 2016 among union households, winning only 51 percent — the narrowest margin of victory for a Democratic presidential candidate since 1984. In Ohio, Trump bested Clinton among union households by 9 percentage points. But the next Democratic nominee could poll more strongly with that group in 2020, Building Trades brass argue, if their voters feel betrayed by Trump. “This is not necessarily what people supported or thought they would get out of this administration,” Monroe said. “The fact that they’re out there engaging on this is something I would think that people in more political circles than I am would probably take notice of.” Sections Political Action