Bill Clinton defends foundation against 'political' attacks

New York (CNN)Bill Clinton is pushing back against the spate of negative stories that have swirled around his family's foundation for months.

In a letter Friday to the Clinton Foundation's 300,000 donors, the former president chalked the negative headlines up to politics and, seemingly, the fact his wife, Hillary Clinton, is running for president. The nearly 1,200 word letter is part of a coordinated effort to engage directly with donors - possibly as a way to quell donor's fears arisen by the negative headlines - and shows the former president is stepping up his push back against the criticism.
"As you all know, it's the political season in America, so the purpose and impact of the efforts your support makes possible has largely been ignored in recent coverage of the Foundation," Clinton wrote. "But we are and always have been a non-partisan, inclusive foundation with lots of support from and involvement by people across the political spectrum and governments from right to left, all committed to our creative solutions-centered work."
The Clinton Foundation has been a flashpoint for controversy in the early days of Hillary Clinton's campaign. From their solicitation of foreign and corporate donations to mistakes made in disclosing speech revenue and tax filings, the foundation has been portrayed as a way for the Clintons to enrich themselves by selling influence.
    Many of the headlines stem from Clinton Cash, a book written by conservative author Peter Schweizer. Though some aspects of the book have been discredited and Schweizer has had to amend some passages, the book has generated plenty of buzz.
    "I am writing to you and our hundreds of thousands of other supporters in the U.S. and around the world to let you know how grateful I am for your support, and for our staff and our partners, and how determined I am that our work will continue," Clinton wrote.
    The foundation does have bipartisan support as Clinton contends. In addition to longtime Democratic donors who have supported the Clintons for years, the foundation has had top Republicans speak at their events - including 2016 Republican presidential hopefuls Gov. Chris Christie and business executive Carly Fiorina. The foundation has also received hefty donations from conservatives, including $1 million from the head of Newsmax, a conservative media outlet.
    Clinton, though, acknowledged some of the reporting mistakes that have plagued the foundation.
    "We will also continue to look for ways to improve our reporting systems so that we can operate as accurately, efficiently, and transparently as possible -- a goal to which we have been committed since day one," he wrote, adding later in the letter that the foundation will "continue to strive for accuracy and transparency."
    Clinton Foundation aides, however, have admitted they made mistakes.
    Acting CEO Maura Pally wrote in a blog post last month, "Yes, we made mistakes, as many organizations of our size do, but we are acting quickly to remedy them, and have taken steps to ensure they don't happen in the future."
    The letter from Clinton continues to detail some of the foundation's projects, including what Clinton and his daughter Chelsea saw on their trip to Africa early this month.
    Clinton writes that his "work with the Clinton Foundation over the past 14 years has been one of the most rewarding endeavors of my life."
    In an effort to show their work continues, the foundation announced Friday that they have partnered with two renewable energy outfits - Rocky Mountain Institute and Carbon War Room - to promote energy efficiency in the Carribbean. The foundation also announced they would hold their fifth annual Clinton Global Initiative America meeting June in Denver.