Wed, Nov 21, 2012 1:47 PM EST

Rep. Jesse Jackson Jr. will announce his resignation from Congress "momentarily" in a letter to House Speaker John Boehner, Jackson's brother Jonathan Jackson told the [Chicago Tribune]( The announcement comes two weeks after Jackson won re-election without campaigning. The 47-year-old Jackson had not been on Capitol Hill since late May. He has been on medical leave [for bipolar depression.](