One of the longest-serving U.S. senators is running for re-election, he announced Friday. Sen. Chuck Grassley (R-Iowa) will seek an eighth term. Grassley, 88, has been in office since 1981. “Serving Iowans in the United States Senate is a tremendous honor. I’m working as hard as ever for the people of Iowa and there’s more work to do,” Grassley said in a statement sent to news outlets early Friday. “In a time of crisis and polarization, Iowa needs strong, effective leadership. I’m focused on serving the people of Iowa as your senator and fighting for policies that will make Iowa an even better place to raise a family and grow a business,” he added. Republicans have held both Senate seats representing Iowa since 2015. Sen. Joni Ernst (R-Iowa) won another term last year. Grassley will face competition in the Republican primary from state Sen. Jim Carlin. Three Democrats have also …