Lou Barletta, the former congressman seeking the Republican nomination for governor of Pennsylvania, has signed a pledge from a conservative anti-tax Washington-based group that commits him to oppose tax increases. The pledge, sponsored by Americans for Tax Reform, commits the signer to the state’s taxpayers to “oppose and veto any and all efforts to increase taxes.” Barletta, of Hazleton, said on Twitter on Friday that he was proud to sign it. As governor, Barletta said, he will lower taxes. Americans for Tax Reform lists 13 sitting governors — all Republicans — who have signed it.