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Rather than ruffle feathers—or worse—Republicans who work there often just keep quiet. Rich Tafel, who coaches tech companies in politics and policy, understands the dynamic. The founder of the gay group Log Cabin Republicans, he's had many Republicans in Silicon Valley confide to him their true political views.

"You just learn how to operate, if you will, in the closet as a Republican," Tafel told National Journal. "You keep your viewpoints to yourself."

One startup CEO who has worked in Silicon Valley for more than a decade says that while it's popular to talk politics in the workplace, the underlying assumption is that everyone has similar views.

The CEO, who generally votes Republican and donates to GOP candidates—he spoke on background to conceal his right-leaning views—said that in 2012, "you wouldn't want to say you're voting for Romney in the election." At the same time, openly expressing one's support for Obama was "incredibly common."

His opposition to raising the minimum wage is just one area where he diverges with most of his colleagues. "If you say something like, 'We need a higher minimum wage,' you don't get critiqued," he said. But he would never reveal his more conservative outlook on the matter.

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"They can't fathom that somebody disagrees with them," he said. "And I disagree with them. So I'm not going to open up that box."

Closeted Republicans aren't just a phenomenon in the tech industry. In Hollywood, where acclaimed movie stars and directors throw lavish fundraisers for Democrats and unabashedly support liberal causes, Republicans are a rare breed. Friends of Abe, a GOP support group of sorts, caters to A-list conservatives in the entertainment industry. Only a handful of its members have made their affiliation known, and its roster is kept secret out of fears of a blacklisting reminiscent of the McCarthy era.

For some right-leaning techies, the GOP brand itself is a liability. The startup CEO stressed that there are "a number of ideas that conservatives have that I totally disagree with," such as opposition to same-sex marriage, and he abhors the thought of being lumped in with Republicans who deny climate change or evolution.

"Republicans are regarded as assholes," he said. "And I wouldn't want to be associated with assholes."

Another Republican who founded a small San Francisco-based startup told National Journal that he's worried potential partners and investors would be turned off by his libertarian views. Recently, it seems like all of his peers in Silicon Valley have been outspoken about their opposition to the thwarted religious liberty law in Indiana, he said. He thinks business owners should be allowed to decide whom they serve, and if they discriminate against gays, people can choose not to patronize their business. He won't discuss that view, though, or debate his left-leaning colleagues on Facebook or Twitter.