It's actually not that hard to figure out:

Rep. Ron Paul (R-Texas) has been known to say "no" to party leadership frequently during the libertarian icon's 11 terms in the House. But his recent decision to reject the House GOP's earmark ban by requesting 41 projects totaling more than $100 million for his Congressional district may not be excused.

Paul is one of a handful of Members to publicly challenge the House GOP leadership by going forward with earmark requests just two weeks after the Republican Conference adopted a one-year moratorium on the spending practice. [...]

[Paul] defended his decision to request projects, saying he needed to make sure his constituents benefited from their federal tax dollars. [...]

Paul said leaders were well aware of his opposition to the ban and his belief that earmarks increase transparency because the public can see where their federal dollars are being allocated.

"They asked me whether I would sign on to the moratorium, and I said no, it doesn't fit my philosophy because I think we should designate every penny that we spend," he said.

Previous Hit & Run commenter scrums on this topic here and here.