Earlier today, Marc Andreessen, made a surprise political donation of $100,000 to Republican presidential candidate Mitt Romney’s SuperPAC. This is a surprise because for the most part Silicone Valley leans very liberal. For Example Facebook COO Sheryl Sandberg and Google executive Marissa Mayer have hosted big fundraisers for Democratic candidates, and Ex-Google CEO Eric Schmidt is a huge Obama booster. Steve Jobs from Apple even once offered to help make commercials for Obama’s 2012 campaign.

The reason why SIlicone Valley leans more left is partially due to the climate of the internet, but also the general feeling around the San Francisco Bay Area where many of the big execs have roots.

In a CNBC interview, Andreessen says he supports Romney because he is a “dyed-in-the-wool” businessman who understand that “regulations” get in the way of business. Andreessen says he used to support Democrats but “I turned 40 last year and so I figured it was time to make the switch.”

Marc Andreessen is best known as co-author of Mosaic, the first widely-used web browser, and co-founder of Netscape. He sits on the board of directors of Facebook, eBay, and HP.