A major alliance of construction unions on Friday will endorse Joe Biden, giving the Democrat a boost from a crucial bloc of blue-collar voters in the final days of his campaign against President Donald Trump.

North America's Building Trades Unions, a coalition of 14 unions representing nearly 3 million workers in the United States, had been on the sidelines as it weighed Trump's policies and the implications of Biden's proposed infrastructure and climate plans.

The coalition has not yet publicly announced the endorsement.

Trump had also courted the union's support, according to a person familiar with the matter, but the group was disappointed by the lack of further coronavirus relief that would also advance union policy goals.

"Joe Biden will deliver for America's working class because he's done it before," Sean McGarvey, the union group's president, said in an emailed statement. "His plan to build a vibrant, sustainable infrastructure and a secure energy future supports union building trades workers and their families."

He described the Trump administration as delivering "four years of broken promises" and a "war on the middle class."

The group endorsed Democrat Hillary Clinton in 2016 but half of their rank-and-file members voted for Trump. Support especially among white working class voters helped Trump win a string of industrial "rust belt" states that paved his path to the White House in 2016.

Biden is competitive in many of those same states, from Michigan to Pennsylvania and Ohio, and has built a large portfolio of endorsements from unions that could benefit from greater infrastructure spending. Biden has also proposed other measures, including a higher minimum wage, coveted by labor.

Both candidates in the Nov. 3 election have been pushing a made-in-America agenda and substantial new federal spending on infrastructure.

Biden, who has criticized Trump for failing to deliver a major infrastructure spending bill, wants to invest $2 trillion over four years into efforts including renewable energy projects to thwart the effects of climate change. Trump has attacked such plans and expressed skepticism on climate change.

At their second and last debate in Nashville on Thursday, Trump criticized Biden for saying, "I would transition from the oil industry." Biden later added that he was talking about subsidies for fossil fuels and that many jobs would exist in alternative energy industries.

"He is going to destroy the oil industry," Trump said. "Will you remember that Texas? Will you remember that Pennsylvania, Oklahoma, Ohio?"

Labor leaders including McGarvey have expressed skepticism as to whether a swift move away from fossil fuels could imperil a major source of construction and other jobs.

A Biden campaign spokesman did not immediately comment on the endorsement.