RICHMOND, Va. (AP) — Sen. Mark Warner doesn’t often sound like he’s working at his dream job. He frequently expresses frustration with the Senate’s slow pace and partisan gridlock and even considered quitting in 2012 to run for his old job as Virginia’s governor. So why does he want a second term? The Democrat says he’s begun to figure out how the Senate works and how he can make it a better place. Warner is facing challenges from Republican Ed Gillespie and Libertarian Robert Sarvis in next month’s election. While Warner’s colleagues in several other states are facing tough re-election prospects thanks in part to President Barack Obama’s sagging popularity, polls in the Virginia contest have shown Warner with substantial leads.