What is pork in political terms?

Answer 1

It's short for "pork barrel spending." A pork project is something paid for by federal dollars that only benefits a limited number of citizens, and that the greater majority of the citizens sees as unnecessary.

Answer 2

Pork refers to specific government funding projects or tax breaks which benefit a specific representatives' riding with little benefit to the rest of the country. Often these projects are ineffectual and a waste of money.

The pork metaphor represents the way pigs feed at a trough, frantically and unrestrained. In this case, the food in the trough is government money.