WASHINGTON (Reuters) - Presidential candidate Donald Trump on Wednesday lashed out at the U.S. Chamber of Commerce’s scathing criticism of his stance on trade, highlighting divisions within the Republican Party that threaten unity ahead of the Nov. 8 election. At a campaign rally in Maine on Wednesday, Trump called the nation’s largest business association “controlled totally by various groups of people who don’t care about you whatsoever.” He said new trade deals should be negotiated because foreign countries are taking advantage of America. “Every country that we do business with us look at us as the stupid people with the penny bank,” Trump said Wednesday at the rally in Bangor, Maine. The Washington-based lobbying group, which represents the United States’ largest companies and business interests, is typically a reliable backer of Republican policies.  But on Tuesday it took issue with Trump’s vocal opposition to trade deals, calling his proposals “dangerous” ideas that would push the United States into another recession. Trump said the Chamber’s argument that his policies would cause a trade war were incorrect because the United States was already at a deficit.  “We’re already losing the trade war, we lost the trade war,” Trump said. “Nothing can happen worse than is happening now.” In speeches on Tuesday, Trump called for renegotiating or scrapping the North American Free Trade Agreement (NAFTA) with Canada and Mexico, calling it a job killer, and reiterated opposition to the pending Trans-Pacific Partnership among the United States and 11 other Pacific Rim countries. He also lambasted China’s trade and currency policies. The Chamber has consistently backed trade deals.      The public squabbling between the presumptive Republican nominee and the business group was unusual, one of a series of reminders that Trump still struggles to unite his party behind his campaign. The Republicans and many business leaders tend to share policy goals and work in lockstep, and many business leaders have traditionally been big donors to Republican candidates. So far, the Chamber’s political action committee has donated $134,000 to federal candidates or their committees, with $127,500 of that total going to Republicans, according to U.S. government campaign finance records. Billionaire Republican donor Paul Singer, who bankrolled an effort to try to defeat Trump during the campaign’s nominating phase, said on Wednesday that a Trump presidency and his trade positions would almost certainly lead to a global depression. “The most impactful of the economic policies that I recall him coming out for are these anti-trade policies,” Singer said during a panel discussion at the Aspen Ideas Festival in Colorado, according to CNBC. But opposing trade deals has proven a winning strategy for Trump among voters concerned about the loss of manufacturing jobs.  Art Laffer, an economic adviser to President Ronald Reagan who supports Trump, said he did not like the tone of Trump’s speech on Tuesday but thought it was an improvement over his past comments on trade. “It’s not terribly alarming to me,” Laffer said. “I didn’t see any 45 percent tariffs across the board. ... “I saw negotiating better trade deals rather than throwing away all the trade deals we have now. He points out the flaws in these trades, and that’s all true,” Laffer said. “I don’t like the tone of it, but I dislike the tone less today than I did three weeks ago.” Peter Navarro, a Trump trade policy adviser, defended the candidate’s position. “Here’s the central point to understand: The White House has been utterly and completely soft on China’s illegal trade practices,” said Navarro, a professor at the University of California, Irvine. “The status quo is the worst of all possible worlds for the United States.”  Trump also took fire from for his positions on trade from Democrats. In a call organized by rival Hillary Clinton’s presidential campaign, U.S. Senator Mark Warner of Virginia, a former businessman and tech entrepreneur, said that while the country needed to do a better job protecting workers, more resources should be put into training them for a new economy. He also noted that it was unusual to see a Republican standard-bearer and the Chamber divide.  “You’ve really got a special circumstance when the U.S. Chamber of Commerce” responded to Trump’s economic plan with a “full-fledged onslaught,” Warner said. “No one could have predicted this kind of election season.” Clinton held no public campaign events on Wednesday but did announce she would appear next week with President Barack Obama, the first time this year that he and his former Secretary of State have campaigned together. 