HARRISBURG (AP) — Lou Barletta, the former congressman seeking the Republican nomination for governor of Pennsylvania, has signed a pledge that commits him to oppose tax increases. Barletta said on Twitter on Friday that he was proud to sign it. The sponsor, Americans for Tax Reform, lists 13 just sitting governors — all Republicans — who have signed it. The last Republican governor of Pennsylvania, Tom Corbett, also signed the pledge. Ultimately, Corbett signed legislation raising taxes on motor fuels and scores of fees. Barletta is running in a crowded field for the GOP nomination next May. Gov. Tom Wolf, a Democrat, is constitutionally barred from serving a third term.