More bad news for the Clintons. With Hillary's presidential campaign slipping in the polls against Sen. Bernie Sanders and facing a potential fresh challenge from Vice President Joe Biden, six giants of the corporate world are bailing out on the Clinton Global Initiative.On Sept. 26 , CGI, a branch of the Clinton Foundation, convenes its 11th annual meeting with a star-studded cast. Bill and Chelsea Clinton will be joined by Ashley Judd, Charlize Theron, Edward Norton, Ted Danson, Tina Brown, Neil deGrasse Tyson, Sir Richard Branson, Bill Gates and George Soros . What will be missing is more than a million dollars from a who's who of corporate behemoths that sponsored the meeting last year. Six high-profile firms ended their cash donations, to be replaced with only one similar high-profile corporate donor so far.USA TODAY has confirmed that sponsors from 2014 that have backed out for this year include electronics company Samsung, oil giant ExxonMobil, global financial firms Deutsche Bank and HSBC, and accounting firm PwC (PricewaterhouseCoopers). Hewlett-Packard, which just announced major layoffs, will be an in-kind donor instead of a cash contributor, and the agri-chem firm Monsanto has cut back its donation. Dow's name is missing from the donor list as well, but the chemical company's exit is not confirmed.High-profile corporations might not be the only key supporters backing away from association with the Clinton family's charitable arm. In 2014, eight national leaders, kings, presidents and prime ministers, appeared on the program for CGI's annual meeting, including the president of the United States and the prime minister of Japan. This year, only leaders from Colombia and Liberia are currently on the programThe Obama administration is backing away as well. In 2014, the cabinet officials heading the Environmental Protection Agency and the Department of Commerce, as well as key White House adviser Valerie Jarrett spoke at the conference. This year no Obama administration appointees as prominent are on the program.In emails, Craig Minassian, chief communications officer of CGI, said that more speakers and sponsors are yet to be announced. The event will be attended by nearly two dozen heads of state. "Revenue is actually slightly better than last year ... so there isn't a decline in support," he wrote.. Questions about ill-considered private email use while secretary of State and about the former first lady's honesty already dog her efforts in Iowa and New Hampshire, where she is no longer considered a sure winner.The corporate skittishness could be driven by a politically toxic atmosphere around the charity. Controversy over foreign donations to the Clinton Foundation while Clinton was secretary of State has tarnished the globally prominent foundation's reputation. Some reporting has raised concerns that corporations and foreign governments were trying to curry favor with Clinton in an effort to influence government decision-making. The sluggish global economy could be a factor as well.In any case, the corporate pullouts can't be a morale builder for Team Clinton, where personnel have shifted freely among campaigns, government service and the family foundation.It is not all bad news. According to the foundation website, Microsoft has increased its donation to the event and well-known retailer GAP, Inc. has joined the roster, but other names signing on are unknown to most Americans: Consolidated Contractor Company , a Middle East construction firm; Delos , a real estate company; and Cheniere , a natural gas pipeline and terminal company.As in years past, a number of widely known corporate brands are sticking with sponsorship of the Clinton event. Barclays, CocaCola, P&G, Cisco, Goldman Sachs and Western Union remain sponsors, as they were in 2014. Senior executives from other companies, including Sodexo and Unilever, will appear on stage. And non-profit support for the event has not dropped off.A Clinton Foundation official told USA TODAY that the changes in sponsorship are not out of the ordinary and that this is not a new trend. But the high-profile turnover appears greater than usual. Last year, Samsung, Monsanto, PWC, HSBC andBlackstone were added as sponsors of the CGI meeting, while Duke Energy, Pfizer, Booz Allen, ApCo Worldwide and Toyota left. The companies that joined tended to donate at higher levels. For example, HSBC joined at the $1 million "Convening Sponsor" level, while Booz Allen, Toyota and Pfizer ended donations at the lowest level of giving, "Meeting Sponsor," representing donations of $250,000.