Right wing organizations with lots of money to spend are targeting Republican's in primary elections who have taken moderate stances on issues dear to them. They are spending more money attacking moderate Republican's than Democrat's are spending against Republican's. Republican's who have not voted to defund Obamacare, and those who voted for raising the debt ceiling are getting most of the attention from right wing organizations. The Republican Party is being radicalized and captured by a small number of organizations that hope to transform the country.
These groups have spent a lot of money teaching the public to hate Obamacare. They use that hatred, in turn, to raise more money from their base. They use the Internet to reach Tea Partiers and tell them that they can vote against Obamacare by sending money to them. Hatred of Obamacare, as well as a more general hatred of a black president, and all of his policies, is a motivation that holds this group together. The GOP has become a party with hatred as its foundation. That serves the traditional base of the GOP very well. There aren't enough plutocrats to win elections. The reactionaries among the plutocrats have found a way to build a populist base that will support its agenda.