I think this article explains it all better than anything else I have read.

House Republicans have proposed spending about $260 billion over nearly five years, but the bill is drawing fire from so many quarters that the ability of Speaker John Boehner, R-Ohio, to muscle the measure through to passage is in doubt. To build support with tight-fisted tea partiers for such a large spending bill, GOP leaders added sweeteners designed to appeal to conservatives, such as expanded offshore oil and gas drilling, approval of the controversial Keystone pipeline and a requirement that federal employees pay more toward their pensions.
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