WASHINGTON (AP) - Lawmakers are streaming back to Capitol Hill after their summer vacation for an abbreviated September session in which feuding Democratic and Republican leaders promise action to prevent a government shutdown while holding votes aimed at defining the parties for the fall campaign. Republicans control the House and want to pad their 17-vote majority, so they intend to follow this simple rule: first, do no harm. Last fall, they sparked a partial government shutdown over the implementation of President Barack Obama's health law.