Party-switcher Sen. Arlen Specter (D-Pa.), who is facing a tough Democratic primary fight next year to remain in the Senate, will speak before the AFL-CIO when the labor group meets for its annual convention in Pittsburgh later this month. Specter, who has indicated his support of a modified version of the Employee Free Choice Act that is a top issue for organized labor, will join a lineup of speakers that includes President Barack Obama, Labor Secretary Hilda Solis, Caroline Kennedy and fellow Pennsylvania Sen. Bob Casey (D). The AFL-CIO convention runs Sept. 13-17.Specter’s appearances come as he faces a tough 2010 primary against a more liberal Rep. Joe Sestak (D-Pa.), who has been hammering Specter over his loyalty to the Democratic Party. Sestak, a two-term Member who announced his Senate bid last month, is not included in the lineup of speakers at the AFL-CIO convention.As a moderate Republican in previous campaigns, Specter enjoyed labor’s support. As a Democrat, he is now wooing the key voting bloc that so far has not endorsed in next year’s primary. “The Senator has always enjoyed organized-labor support. He was endorsed in the 2004 campaign. We hope to have that support again this year,— Specter campaign spokesman Chris Nicholas said. Specter has been engaged in closed-door negotiations with Democratic Sens. Tom Harkin (Iowa), Charles Schumer (N.Y.), and a handful of moderates such as Arkansas Sen. Mark Pryor (D-Ark.) to try to broker an agreement on the Employee Free Choice Act, otherwise known as “card check.—A Specter spokeswoman said that at the AFL-CIO convention Specter will “talk about his work for labor— and predicted questions about the card check bill “will probably come up.—