WASHINGTON — President Biden announced plans Wednesday for a new 15% tariff on Chinese steel and aluminum as he stumped for votes in Pittsburgh — resuming former President Donald Trump’s trade war with Beijing after a three-year lull.

“For too long, the Chinese government has poured state money into Chinese steel companies, pushing them to make so much steel, as much as possible, subsidized by the Chinese government,” Biden said in a speech to members of the United Steelworkers union.

“Because Chinese steel companies produce a lot more steel than China needs, it ends up dumping extra steel onto the global market at unfairly low prices.”

“They’re not competing, they’re cheating,” Biden added, “and we’ve seen the damage here in America.”

US-China relations, including on trade, are a major Trump campaign focus as the former president seeks a rematch against Biden in the November election.

The Trump campaign pointed to Biden’s past support for China joining the World Trade Organization in 2001 in a Wednesday email blast with the subject line, “Joe Biden Spent His Entire Career Betraying Working Americans — Now, It’s Too Little, Too Late.”

The tariff increase isn’t necessarily a sure thing — as Biden said he was merely “calling on” US Trade Representative Katherine Tai “to consider” higher tariffs upon reviewing Trump-era policies on China.

Biden, 81, said he also wanted his administration to “work together” with Mexico to prevent Chinese steel companies from laundering their products to avoid tariffs.

The president said he additionally was ordering the start of an investigation into whether Chinese shipbuilders are engaged in trade violations that would justify a US response.

Administration officials previewed the moves in a press call late Tuesday — saying China was poised to flood the US market with cheap steel and aluminum, undercutting American manufacturers.

“China’s policy-driven overcapacity poses a serious risk to the future of the American steel and aluminum industry,” one official said.

“In manufacturing sectors like steel, China’s already producing more than China or the world can easily absorb.”

Biden’s plans for more tariffs emerged as he sought votes in steel-producing Pennsylvania, where Trump narrowly won in 2016 by vowing to change trade relations to boost domestic industry.

The state is expected to be one of just a handful that tips the balance between Trump and Biden this year.

Biden has kept in place most of Trump’s China tariffs, including a 25% tariff on steel and 10% tariff on aluminum from most countries, which Trump imposed in 2018 under Section 232 of the Trade Expansion Act of 1962.

Trump slapped other tariffs on China under an authority known as Section 301 — with levies between 7.5% and 25% still in effect under Biden on an array of Chinese goods comprising roughly $362 billion of annual imports, or more than half of the overall volume from China.

Biden’s new 15% tariff on Chinese steel and aluminum would be done under Section 301, under which there’s already an average 7.5% tariff on such products, according to Tai’s office.

The former president’s escalation with China was part of a plan to force a grand new trade pact to improve US standing, which stalled when the COVID-19 pandemic hit in March 2020, just two months after Trump and the Chinese government agreed to a “Phase One” bundle of reforms.

Republicans have accused Biden of being too soft on China on a variety of issues, including stopping exports of synthetic opioids such as fentanyl, which have killed more than 200,000 Americans since Biden took office.

Critics also fault Biden for not pushing harder to determine the origins of the COVID-19 pandemic, which killed nearly 1.2 million Americans after potentially leaking from a lab in Wuhan, China.

Trump claimed in August that Biden “was bribed and now he’s being blackmailed” by China.

Biden recently has adopted some tougher policies toward Beijing — invoking saying last month that he would sign a House-passed bill that would force the sale of Chinese-owned TikTok.

The House impeachment inquiry into that’s focused on alleged Biden family corruption, meanwhile, has probed two Chinese government-linked ventures involving the president and his relatives.

In 2013, Biden met in Beijing with Jonathan Li — the incoming CEO of Chinese state-backed investment fund BHR Partners, in which his son Hunter Biden held a 10% stake until recently — the first son testified in February, confirming prior reporting by the Wall Street Journal.

Joe Biden later greeted Li on speaker phone during another visit by Hunter to China, his former business partner Devon Archer testified in July, and wrote college recommendation letters for Li’s children.

The terms of Hunter’s alleged divestment from BHR Partners remain murky.

As part of a separate Chinese government-linked business venture, Joe Biden met CEFC China Energy Chairman Ye Jianming at the Four Seasons hotel in Washington in 2017 weeks after he left office as vice president, former Biden family associate Rob Walker testified Jan. 26.

Walker said that Joe Biden met Ye shortly before CEFC transferred $3 million in March 2017 to a consortium of Biden family associates for work scouting business opportunities while Biden was still vice president. Ye has since gone missing amid corruption allegations in China.

More than $1 million of the haul flowed to Hunter and first brother James Biden.

A subsequent May 2017 email written by Biden family associate James Gilliar penciled in a 10% stake in a CEFC joint venture for the “big guy,” whom multiple former associates have identified as Joe Biden, though it’s unclear that he ever actually was awarded such a share.

The Bidens in mid-2017 cut out their partners and Hunter invoked his father in a threatening text message in July 2017 warning a Chinese CEFC associate to follow through with an agreed upon financial arrangement and that he was “sitting here with my father,” according to documentation provided to Congress by IRS case agent Joseph Ziegler.

Photos from Hunter’s abandoned laptop show he was at his father’s Wilmington, Del., home on the day of the message, but Ziegler and his supervisor at the IRS, Gary Shapley, testified they were blocked by the Justice Department from acquiring cellphone geolocation data that could have proven the men were indeed sitting together.

Within 10 days of the message, $5.1 million flowed to accounts associated with Hunter and James Biden, according to information in a 2020 report by Republican-led Senate committees.

James Biden confirmed to Congress in February that he paid Joe Biden $40,000 on Sept. 3, 2017, from funds he received from CEFC for what he said was a short-term loan. There are no known loan documents.

Hunter Biden faces an upcoming trial in Los Angeles for allegedly failing to pay taxes on foreign income — after walking away last July from a probation-only plea deal over his courtroom demands for assurances of immunity for other conduct, such as alleged violations of the Foreign Agents Registration Act, which could implicate his father.