The unusual battle between Donald Trump and much of the Republican establishment on international trade is rapidly escalating, as the presumptive GOP nominee rails against business groups and members of his own party while defenders of sweeping free-trade pacts rebuke him.

The rift deepened on Thursday when Trump called out the U.S. Chamber of Commerce by name for the second straight day and pilloried the North American Free Trade Agreement and the ­Trans-Pacific Partnership, two landmark trade agreements broadly supported by Republicans.

“I’m messing with bad deals that we could make good,” Trump said in his speech at a shuttered manufacturing plant in Manchester, N.H. “I could make good deals. Why would somebody fight that? I mean, the U.S. Chamber fights. They said, ‘Oh, Trump wants to stop free trade.’ I don’t want to stop free trade. I love free trade, but I want to make great deals.”

The mogul’s comments followed a flurry of insults throughout the week aimed at advocates of broad trade accords, which have been championed by Republican leaders for decades as crucial engines of capitalism. Trump accused TPP backers, for example, of wanting to “rape” the United States.

For Trump, feuding with powerful business interests makes him an attractive candidate for many disaffected working-class voters, including some who have supported Democrats in the past.

Speaking at a campaign even in Manchester, N.H. June 30, Republican presidential candidate Donald Trump suggested a plane flying over head could be "a Mexican plane up there; they're getting ready to attack." (Reuters)

But the loud dispute also risks alienating many of the Republican Party’s wealthy benefactors at a time when he is struggling to kick his long-dormant fundraising operation into gear. A stridently protectionist message could also push some moderate Main Street Republicans to support Democratic rival Hillary Clinton, in much the same way that many Republicans in the foreign policy world have done.

[Wonkblog: Donald Trump’s trade war could kill millions of U.S. jobs]

Many business groups, which generally favor looser trade restrictions and are traditional Republican allies, have taken sharp issue with Trump’s latest comments and appear determined to rebut them.

“While we never endorse in the presidential race, we do plan to be aggressive in presidential policy with both major party nominees,” said Scott Reed, the senior political strategist at the Chamber of Commerce. The group repudiated Trump in real time on Tuesday in a series of tweets as he delivered an address threatening to tear up trade accords and impose tariffs.

Trump has long blamed broad trade agreements for harming U.S. workers. But this week has marked a rhetorical shift as he aggressively casts members of both parties who have supported trade deals as anti-American and in league with “special interests.” For many Republicans in particular, the rhetoric amounts to an assault on core ideological beliefs that have undergirded conservative economic policy for generations.

The candidate’s arguments have also left an opening for sharp attacks by Clinton and other Democrats accusing him of hypocrisy. Trump in the past has talked favorably about outsourcing jobs overseas, and much of his Trump-branded apparel line and other products are manufactured in low-cost Asian countries.

“Donald Trump is running as an anti-Republican Republican in many ways,” said David French, senior vice president of government relations at the National Retail Federation, which like the Chamber of Commerce is not taking sides in the presidential contest. French said Trump’s commentary on trade has been disappointing.

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Some business leaders are privately pessimistic that publicly fighting Trump hard on trade will be a winning proposition. His access to free media coverage through television and radio interviews presents a big obstacle to anyone standing in his way.

It also remains to be seen how and if these groups will escalate their fight beyond social media and chastising in the news media. The Chamber of Commerce, for example, is focused heavily on down-ballot contests and, given that the group primarily supports Republicans, could end up helping Trump regardless.

[Fact Checker: Donald Trump’s claim that China ‘will enter’ the TPP ‘at a later date’]

As Trump spoke Thursday, he stood in front of a manufacturing facility that closed in 2014, causing more than 130 workers to lose their jobs. He continued to tout his protectionist economic policies, which he has underscored since the day he launched his campaign more than a year ago and which stand at odds with many pro-free-trade statements in his past.

Trump’s repeated needling of the Chamber of Commerce, which is the nation’s largest business lobby, signaled that he has found a new favorite target. During a rally in Maine on Wednesday, Trump accused the organization of being “totally controlled by the special-interest groups.”

The mogul continued his assault on social media a few hours later, tweeting, “For reasons only they can explain, the @USChamber wants to continue our bad trade deals rather than renegotiating and making them better.”

Trump has repeatedly blamed outsourcing and big trade agreements for domestic economic decline. He has vowed to renegotiate NAFTA as president and withdraw the United States from TPP — promises many experts in both parties call unrealistic and highly risky.

But such talk has won Trump legions of fans in the economically depressed Rust Belt and other areas suffering from the effects of globalization. His allies hope it will help him compete in Ohio and Pennsylvania, two key swing states.

Trump’s repeated talk about trade is aimed in large part at undermining Clinton, whose husband signed NAFTA as president. Trump also accuses Clinton of waffling on TPP, which she praised as secretary of state but then opposed during her hard-fought primary contest with Sen. Bernie Sanders of Vermont.

“The trade policies of Hillary Clinton, global financiers — and they’re all controlling her, they have 100 percent, they might as well stamp Hillary Clinton on their forehead,” he said Thursday.

Clinton and other Democrats have pushed back by pointing to the ways that Trump has benefited from the policies he now condemns. On Thursday, Clinton issued a tweet listing the countries, from Mexico to Bangladesh, where Trump-branded ties and shirts were made.

While Trump insists he is not trying to challenge free-trade principles, he has repeatedly argued that it is more important for the United States to have “fair trade” agreements. He has said that he would prefer to negotiate deals one-on-one with countries rather than enter into multi-national settlements.

[The Fix: Donald Trump’s opposition to free trade is savvy — and a sign of how he’s changing the GOP]

Trump has repeatedly vowed to impose high tariffs — or the threat of high tariffs — to bully American companies into keeping jobs in the United States. His favorite example is Ford Motor Co., which plans to build a massive plant in Mexico. Trump has said that before he takes office he will persuade Ford to change course by threatening to charge the company a 35 percent tax on cars imported back into the United States.

Trump took a handful of questions from the audience Thursday, including one from a man who used to work at a factory that made police badges but lost that business when departments started ordering from overseas.

“What are you going to do for us?” the man asked, as the small crowd applauded.

“First of all, your story is common to thousands and thousands of companies throughout this country,” Trump said, before promising to fight currency ma­nipu­la­tion, which he says makes it impossible for U.S. companies to compete with those based in China and elsewhere.

Trump repeatedly said that while making products within the United States might be a bit more expensive, it’s worth the cost to have more jobs based here.

Another man asked Trump how he will respond to the corporate backlash to his trade policies.

“Corporations? I’m not worried about it,” Trump said, pointing out that his tax plan is “cutting business taxes way down” and that he will make it less expensive for companies to temporarily bring their money back from overseas.

“We will do things that are going to be so miraculous — and it’ll be fast. It won’t take a long period of time,” Trump said.

Jose A. DelReal contributed to this report.