President Barack Obama, who frequently has tussled with corporate America, now is relying heavily on an array of large U.S. companies to help enact a major Pacific trade deal. From Hollywood studios to drug makers and manufacturers, such as Caterpillar Inc., some major American companies are lending key support in the complicated push to negotiate the 12-nation Trans-Pacific Partnership and to win votes in Congress. The administration’s trade quest faces an uphill battle in the House, starting this week. “Our interests on this issue are aligned,” said Myron Brilliant, executive vice president and head of international affairs at the U.S. Chamber of Commerce. “We welcome that engagement. We wish we had gotten it sooner, but it’s better now than never.” For the Obama administration, the new corporate détente marks a shift from prior political battles, when large companies and banks joined Republicans in seeking to defeat the Dodd-Frank financial overhaul, with some also opposing the Affordable Care Act. Mr. Obama and corporations have been at odds during his two presidential terms on the administration’s approach to regulation, taxes and legislative changes affecting industries. In December 2009, less than a year into his first term, Mr. Obama drew ire from Wall Street when he referred to them as “fat cat bankers.” The relationship with businesses in general has remained strained since then. Companies have pushed back, at times with litigation, on administration regulations affecting a number of industries. Among them are signature Obama initiatives on climate change, including an Environmental Protection Agency proposal to cut carbon emissions. The newfound alliance between the White House and big business also is drawing criticism from labor unions, Democrats and conservative lawmakers suspicious of corporate interests, and even left-leaning economists previously supportive of lifting trade barriers. “The administration is in bed with the multinational corporations,” said Democratic Rep. Rosa DeLauro of Connecticut, one of Mr. Obama’s fiercest critics on trade. A White House official said Mr. Obama has the support of a wide coalition on this issue, including businesses of all sizes, state and local leaders, and environmental and other groups. Mr. Obama and his team also are emphasizing the potential upside of the Pacific agreement for small businesses. Certain tariff breaks, the removal of red tape at the border and the lifting of the amount of goods that can be shipped duty free are among the benefits cited. In perhaps his most overt nod to corporate interests in the trade fight, Mr. Obama in May delivered a speech defending the TPP at Nike Inc., which is lobbying more intently on the issue than any other U.S. company, according to lobbying disclosures compiled by the Center for Responsive Politics. “All the suppliers to Nike or Boeing or G.E. or any of these other companies understand this is going to be critical to their growth and their ability to create new jobs,” Mr. Obama said at Nike’s Beaverton, Ore., headquarters. Some large U.S.-focused manufacturers, however, are against the TPP deal. Ford Motor Co. has been critical of the trade agreement, which would reduce U.S. tariffs on Japanese cars over time. Executives from the Detroit auto maker have pressed lawmakers on Capitol Hill to include rules to punish alleged currency manipulation overseas. Blue-chip companies and their defenders contend it’s natural that they’re engaged in fighting for the Trans-Pacific Partnershipas well as “fast track” legislation needed to expedite the dealbecause they have so much at stake as the country’s leading importers and exporters. “Even in a perfect world, this is a heavy lift politically,” said Bill Lane, Caterpillar’s global governmental affairs director. Recently, Boeing Co. hosted Secretary of State John Kerry for a speech backing the Pacific deal as well as the renewal of the Export-Import Bank, which helps fund purchases of Boeing aircraft. Two days later the company’s chief executive, Jim McNerney, visited Capitol Hill as lawmakers sought to tie its renewal to the trade legislation. Mr. Lane, who lobbies lawmakers on Capitol Hill, says Caterpillar saw its exports to Chile triple two or three years after it enacted a trade agreement with the U.S., buoyed by better access to the Chilean mining-equipment market as well as higher prices for copper. The following day, the Senate voted to approve fast track, which would help negotiators conclude the TPP and expedite congressional approval of the deal, with no amendments allowed. The legislation now faces a difficult path in the House, where many Republicans are skeptical of fast track and few Democrats support the measure. After Nike, pharmaceutical companies led by Pfizer Inc. are among the most active entities lobbying on the TPP issue, according to the filings. Drug maker executives and industry groups traveled to the most recent round of TPP negotiations in Guam in late May to back stronger intellectual-property protections in the TPP, a major unresolved issue. Pfizer is backing U.S. trade representative Michael Froman, a former Citigroup Inc. executive, as he seeks to negotiate rules that would protect potentially lucrative biologic drugsmade from living cells, blood components and tissuefrom imitators for up to 12 years, or far longer than the current protection in most TPP countries. Hollywood studios are also pushing for stronger intellectual property rules in the TPP, and big insurers and other financial firms are eyeing greater access in fast-growing Asia. Leading business groups regularly meet with administration officials on the deal, Mr. Brilliant said. The corporate push that helped the legislation in the Senate won’t necessarily have the same force in the House. “For most House Republicans, they’re not as sympathetic to the large multinationals like, Boeing and G.E., unless you happen to have one of those in your district,” said Rep. Charles Boustany (R., La.), who is working to build support for fast track. Instead, the Obama administration and Republicans leaders are relying in part on farmers and farm groups to buttress support in rural congressional districts.