Familiar alliances were scrambled last week when a big blue-collar union and several Democratic lawmakers hailed President Donald Trump’s tariff move.

Leo Gerard, president of the United Steelworkers, long has supported tariffs on foreign steel in response to China and other countries undercutting U.S. manufacturers by dumping excess product here.

“One of the markets they’ve been depressing on an aggressive basis for 25 years is America,” Gerard told Fox News. “They have an almost $600 billion trade surplus with the rest of the world on steel.”

The union has more than 860,000 members across the U.S. and Canada. Gerard, who’s from Ontario, became its president in 2001.

Ohio State University Professor Ned Hill argued that the Trump measure helps older workers on the edge of retirement but not younger workers.

Newer employees “are coming into the plants because the plants have been hiring for the past 2 1/2 years,” Hill said. For them, the tariff is “dicier” due to prospects for trade war and recession in coming years, he told National Public Radio.

Gerard called Hill’s analysis “full of malarkey, as Joe Biden would say.”

Gerard said economists such as Hill simply are suggesting that companies be allowed to deal with cheaters so they can save operating costs.

Rust Belt Democrats also rode the tariff train while top Republicans called for stopping it.

Sens. Sherrod Brown of Ohio, Joe Manchin of West Virginia and Bob Casey of Pennsylvania are all top GOP targets on Election Day. This is now one of the issues setting them apart from the caucus of Senate Majority Leader Mitch McConnell (R-Ky.).

“I’m happy to see action being taken,” Casey told Politico. Brown called the measure “long overdue for shuttered steel plants across Ohio and steelworkers who live in fear that their jobs will be the next victims of Chinese cheating.”

Don’t expect cross-partisan backing for tariffs to spread to other issues.

On NPR, Gerard said his members “got a lot of other things that they’re concerned about like a huge tax cut that’s going to the rich, like the dismantling of our health care system, like cutting back on safety laws at the workplace and a whole bunch of other issues.”

Sen. Jeff Flake (R-Ariz.) has threatened to introduce legislation to nullify the steel and aluminum tariffs. But any such bill starts out as an extreme long shot.

Tariff foes like to note the 1930 Smoot-Hawley tariff law was widely blamed for worsening the Depression. Rejecting the comparison, Trump trade adviser Peter Navarro has promoted Trump’s tariff as defensive, not protectionist.

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