Sentence:  By its nature <WSD>logrolling</WSD> pays off concentrated group interests and ignores diffuse interests, like taxpayers, who are hard to organize. Since interests in expansion and militarism are typically more concentrated than the interests opposed to them, <WSD>logrolling</WSD> is inherently more apt to produce overexpansion than underexpansion. 
Meaning of the word marked with <WSD> tags:  A concerted effort to push forward mutually advantageous legislative agendas by combining two items, either or both of which might fail on its own, into a single bill that is more likely to pass.