Jamie Dimon, chief executive of US banking behemoth JPMorgan Chase and one of the most prominent figures on Wall Street, faces a major challenge to his leadership next week in the wake of the \"London Whale\" debacle. Dimon\'s fate will be determined Tuesday at JPMorgan\'s annual meeting in Tampa, Florida, in a vote on a shareholder proposal that aims to strip him of his concurrent post as chairman after the company lost $6.2 billion in an out-of-control derivatives trading operation last year. A similar proposal last year won 40 percent of the votes, but that was before the full scope was known of the London Whale debacle -- so-called because of a nickname for one of the key traders involved. Authors of the proposal say the bank\'s current power structure entrusts too much power in the charismatic Dimon and lacks the critical check of an independent chairman who can stand up to the CEO. JPMorgan parries that its performance under Dimon holding both posts has been outstanding compared with peers and that its response to the trading losses has been extensive, including cutting Dimon\'s compensation in half.Dimon himself clearly wants to retain both positions, and reportedly suggested to investors privately that he could leave the bank entirely if forced from the chairmanship. At stake is leadership of the largest US bank, by revenue, and the fate of the executive who steered it through the 2008 financial crisis to widespread admiration. Since then Dimon has also prominently fought Washington\'s regulatory efforts to rein in the banks after being forced to bail many out. The shareholder proposal cites an investigation that showed Dimon did not inform key board members of risk limit breaches four months before disclosing the whale problem. That was \"a serious governance failure which may stem from a lack of clarity regarding his authority,\" their letter says. Splitting the roles would restore the bank\'s credibility with regulators, said Lisa Lindsley, director of capital strategies at public employee union AFSCME, whose pension plan owns about 75,000 shares of JPMorgan. Influential proxy advisory services ISS and Glass Lewis have endorsed the initiative -- as well as the ousting of several other members of the JPMorgan board. ISS said three members of the bank\'s risk policy committee \"appear to lack robust industry-specific experience,\" and it accused the board generally of being too passive. Under JPMorgan\'s corporate bylaws, directors who receive less than a majority support are required to offer their resignation. Wall Street is split over the issue of separating the chairman and CEO roles. Analyst Marty Mosby at Guggenheim Securities said the resolution is \"counterproductive\" given Dimon\'s record. \"You can create a kind of rift between the board and management if you insert someone that does not have any history of the situation, yet is placed there to try to police what\'s going on,\" Mosby said. Marshall Sonenshine, chairman of investment bank Sonenshine Partners, supports the split. \"Wall Street thinks it can do everything,\" he said. \"But clearly five years after the financial crisis, if there\'s anything at all that we know for certain it\'s that Wall Street cannot do everything itself well. It doesn\'t regulate itself well and it doesn\'t govern itself well.\" The resolution is non-binding, so the board can choose to ignore a majority vote against Dimon. But doing so would be at the board\'s \"peril\" and would likely trigger even a stronger shareholder campaign next year, said Charles Elson, a corporate governance expert at the University of Delaware. Lindsley said she was \"highly confident\" the proposal would garner more votes than last year\'s. But she is not sure it would win a majority. Yet even a 40 percent vote is significant. It \"says an important segment of shareholders are not happy, or have concerns, about the issue of independent board leadership,\" Lindsley told AFP. Some analysts say the board could chart a middle course, stripping Dimon of one of his roles while ensuring that he maintains a hand over major decisions. He could step down as chief executive but continue to exercise power as chairman, said Mosby. \"You split the roles, but Jamie\'s still on top of the house and he can still drive the ship from there,\" Mosby said.