Businesses support candidates to gain access and influence policy. Whatever the long-term implications are for their policy, in the short-term, their influence on government benefits them directly. For example, changing the laws around interstate banking allows for huge consolidation for the big banks. They need votes of both democrats and republicans to get bills out of committee, and to control the debate on the floor -- no poison-pill amendments, etc.
Republicans control the 3 branches of government, and are dominant at the state level in many states. Grover Norquist (quoted in the article) has consolidated influence over lobbyists on K street so that they're mostly Republican in sympathy. The media are biased in favor of the "Reds." Everywhere a businessman looks, he sees a republican under the bed. Thus, if they want to get their bills passed, it seems they're increasingly coming to the conclusion that they need to deal with the republicans. Grover Norquist is trying to make it an exclusive thing.
If you're not familiar with his work (he's a very dangerous man - vile and effective), check it out here:
http://www.disinfopedia.org/wiki.phtml?title=Grover_Norquist