Three of the Democrats running for President will speak at this weekend’s convention of the largest union for government workers — AFSCME. The union’s endorsement could be valuable in Iowa, where AFSCME members helped Democrat Tom Vilsack win Iowa’s Governorship back in 1998. Massachusetts Senator John Kerry speaks to the group this evening, and he says he’ll talk about the Bush Administration’s “assault” on workers’ rights..Kerry says the Attorney General is “stomping” on workers’ rights and is trying to destroy some of the rights Americans have in the workplace. Kerry says the Bush Administration is “the most anti-labor, anti-worker Administration” he’s seen in all the years he’s been in Washington. Kerry has been in the U.S. Senate for 19 years. Former Vermont Governor Howard Dean speaks to the group late this afternoon. Dean says he’ll focus on his ideas for creating jobs and a system that’d provide health care for all Americans. Dean says he’ll also tout his campaign’s ability to bring new voters into the fold. Dean, who is a doctor, was Vermont’s Governor for 12 years, and left office in January. Ohio Congressman Dennis Kucinich speaks at the AFSCME convention tomorrow. In other campaign news, Connecticut Senator Joseph Lieberman’s Iowa campaign manager has resigned, citing family reasons. Lieberman says he plans to add staff in Iowa,and he’s asked a state Representative from Des Moines to take over as campaign manager.