(Reuters) – Billionaire investor Daniel Loeb’s hedge fund Third Point LLC disclosed on Thursday it has partnered with fellow Campbell Soup Co (CPB.N) shareholder George Strawbridge to call for a sale of the iconic U.S. food company best known for its canned soups. The move, first reported by Reuters earlier on Thursday, represents one of Loeb’s biggest challenges as an activist shareholder. The descendants of former Campbell Soup Chairman John Dorrance collectively own about 41 percent of the company, making it difficult to put pressure on it without their support. Third Point and Strawbridge together own a 8.42 percent stake in the 150-year-old company, with Third Point itself owning 5.65 percent, according to a regulatory filing with the U.S. Securities and Exchange Commission. Third Point said it believed that a strategic review underway at Campbell would create “significant value” for shareholders if conducted properly. Third Point also said it may seek board seats at the firm, if it feels that Campbell’s directors have failed to do their job appropriately. Campbell did not respond to a request for comment. Its shares rose as much as 4 percent on the Third Point news. The 56-year-old investor came to Campbell after Campbell Chief Executive Denise Morrison unexpectedly stepped down in May. His departure followed the company’s release of a bleak forecast for the year, when it said it would embark on a review of its many brands. Rival activist shareholder Carl Icahn also considered an investment in Campbell, but decided against it because the family dynamics would make it tough to press for big changes, according to a source familiar with the matter. Icahn’s office declined to comment. Campbell’s annual meeting was held in early November last year, which means that Third Point would have a relatively short period of time to nominate potential directors if Loeb plans to mount a board challenge later this year. Loeb’s $18 billion hedge fund has a history of making investments in food companies, including most recently Nestle SA (NESN.S), where it has been pressing management to spin off some units and streamline the portfolio. Campbell in 2015 reorganized into three divisions, creating the Campbell Fresh unit after combining what was a packaged fresh division with soups sold to supermarket delis. But Campbell Fresh struggled, resulting in a two-year decline in organic sales. Campbell has said it expects to discuss the outcome of its strategic review when it reports fourth-quarter results in late August. Analysts have said that the most logical path for the company may be to separate its profitable but debt-laden snack business from its slower-growing soup business. While Kraft Heinz Co (KHC.O) considered an acquisition of Campbell in the past, it is not currently exploring a bid, according to a source familiar with the matter. Kraft Heinz did not respond to a request for comment.