President Obama's rhetorical war against Wall Street "fat cats" and his efforts to enact sweeping reforms of the financial sector haven't exactly endeared him to top financial industry executives.

Now it appears the Wall Street donors who helped fund Obama's successful 2008 bid are shifting their campaign cash elsewhere.

Per Bloomberg's Jonathan Salant, at least 100 donors who previously supported Obama in 2008 haven't written a check to his re-election campaign and are instead supporting Mitt Romney's 2012 bid. The shift has helped Romney raise more than twice as much from Wall Street as Obama has so far this election cycle.

Democrats close to the Obama campaign downplay the shift, insisting it's no surprise that Romney, a former finance executive, has outraised Obama among Wall Street donors. The shift in giving also insulates Obama from the idea that he's Wall Street's favorite candidate—a distinction that might not sit well with the president's progressive supporters, who have already complained about Obama's ties to the financial industry.

But it's something that the Obama campaign appears to be worried about. Over the summer, Obama held a sit down with top Wall Street executives, many of them donors, as a way of offering an olive branch to the industry.

There's a reason Obama might want to make nice: According to the Center for Responsive Politics, he raised nearly $15 million from the securities and investment industry in 2008, which ranked as one of the top 5 industry donors to his campaign.

But Obama hasn't had nearly as much success with Wall Street this year. According to CRP, Obama has raised just $857,362 from donors linked to the securities and investment sector, compared to Romney's more than $2.3 million.