In making the announcement, published in a post on Barzun’s blog, the US ambassador said he was “honoured” to be asked to serve as chair of Obama’s National Finance Committee, but regretted the decision would cut short his time in Sweden.

“I am honored to be asked to serve in this new capacity, and am accepting the president’s call,” Barzun wrote.

“However, because of the nature of American presidential elections, it means I will have to leave this post all too soon — at the end of May.

When asked by The Local, the US Embassy provided this additional comment from ambassador Barzun.

“I am honored to be tasked with a new mission by the president. It will be a great challenge, but it’s one that begins for me on June 1st, not today. Until then, I remain ambassador to Sweden with my full attention devoted to this vital work.”

Barzun arrived in Stockholm in August 2009, having being named Obama’s top envoy in June after playing a vital fundraising role for the US president’s successful 2008 election campaign.

During his time serving on the National Finance Committee for the 2008 campaign, Barzun helped pioneer grassroots fundraising events which catered to small donors.

“The idea was, ‘Don’t just go after people who can write $2,000 checks, let them write checks for $25’,” he told The Local in a December 2009 interview .

According to statistics from the Center for Responsive Politics, an independent research organization that tracks money in politics, Barzun helped raisemore than $500,000 for the Obama campaign during the 2008 election cycle.

Part of the total raised by Barzun included more than $290,000 in overall contributions from Barzun and his family to various Democratic candidates, party organizations and political action committees (PACs).

The nearly $300,000 given by Barzun and his family put him as the sixth highest contributor to Obama’s campaign, according to the Center for Responsive Politics.

During his time in Stockholm, Barzun has worked to sustain cooperation between the United States and Sweden in promoting green technologies, establishing the Swedish American Green Alliance (SAGA) in February 2010.

“To meet our urgent climate challenge we must spread ideas faster, and the best vehicle ever devised for this is still story telling. We want to develop and share success stories around sustainability — and do so as quickly as possible — in order to carry our common SAGA forward,” Barzun said at the time.

In announcing his empending departure, Barzun again praised Sweden’s efforts to promote climate-friendly solutions and commitment to acting on the global stage.

“From Sweden’s leadership in sustainability and clean energy to its deep sense of international responsibility, as we have seen most recently in Libya, to the sense of balance embedded in the Swedish national character, I have soaked it all up and become forever enriched,” he wrote.

Born in New York, Barzun was raised in Massachusetts and graduated from Harvard before joining CNET in 1993, helping the company to capitalize on the internet’s rising popularity.

After a successful initial public offering in 1996, CNET was later purchased by US broadcasting giant CBS for $1.8 billion in 2008, by which time Barzun had risen to the position of executive vice president.

Barzun is married to Brooke Brown Barzun, a native of Lexington, Kentucky. The couple have three children.