In political science, they say all politics are local. This basically translates into the political dictum that for someone to win an election, the candidate must be able to connect with local issues and that concerns local and common people.
Henceforth, whether you are running for a local or national post, your best strategy is to remain locally focused. This explains why congressmen do not want to part ways with their pork barrel even if dispensing projects and financial favors in their districts is not really part of their mandate.
This may also partly explains the discrepancy in the last election where majority of the Filipinos voted for senatorial candidates known to oppose GMA while opting to elect congressmen who are avowedly loyal to the president. The former is seen serving the national interest while the latter serves that of the local people. There is however something wrong with this analogy as we saw with the junking of the recent impeachment complaint against GMA.