Tom Williams/CQ-Roll Call, Inc via Getty ImagesRep. Mark Green (R-TN), the chairman of the House Homeland Security Committee, made a surprise announcement on Wednesday that he plans to retire at the end of his current term, his third, a day after leading a successful effort to impeach Department of Homeland Security Secretary Alejandro Mayorkas.“At the start of the 118th Congress, I promised my constituents to pass legislation to secure our borders and to hold Secretary Mayorkas accountable,” Gr