The most powerful business leaders in the world have warned that a Trump trade war could be the greatest threat to their industries since the Second World War.

The threat comes as Trump prepares to release a trade plan this week that he hopes will win his support.

Trump, whose campaign has largely focused on foreign trade, has been pushing the idea of a trade war as he tries to build a coalition of support among the American public ahead of the November elections.

In an op-ed for USA Today, more than 20 prominent business leaders said that if Trump were to adopt a trade policy that would hurt their industries, their businesses would lose billions in trade revenue and the country would face a trade deficit with China.

“We need to be prepared to face this threat,” said David Sirota, chief executive of the National Retail Federation, a trade group.

“If he were to enact a policy that hurt our industries, we would lose millions of jobs and thousands of good-paying jobs.”

Trump’s trade policies have sparked concern among Democrats that they would hurt American workers, while liberals have decried them as “job killers” and a drag on the economy.

Trump, however, has repeatedly said that the country is stronger when American workers are employed and are protected from outsourcing and competition from foreign nations.

The leaders’ views on trade echo what President Barack Obama, who won reelection in 2016, has said repeatedly.

“The Trump trade policies would be the biggest economic stimulus package since the Great Society and would create millions of new jobs and lift millions out of poverty,” Obama said in a speech at the U.S.-China Economic Leaders’ Forum in April.

Trump has repeatedly dismissed the economic benefits of a border wall or other measures to curb imports from China, saying they would be “disastrous” and hurting American workers.

Trump has also called for a border tax, saying that it would be paid for by American taxpayers.

The president has also argued that trade with China is not just a threat to American workers but to American jobs and to the economy as a whole.

“If we continue to ignore the threat posed by China, then we will have lost our manufacturing base, we will continue to have a trade surplus with China, and we will lose jobs,” he said at a debate last year.

“It is the worst threat to our country’s future that has ever been posed.”

Trump has proposed raising tariffs on goods from China and Mexico, including autos, automobiles and machinery.

He also wants to impose a 20 percent tax on Chinese imports, while a proposal by the National Economic Council to reduce tariffs on Chinese products has been rejected by lawmakers.