-LRB- CNN -RRB- -- Monica Conyers , Detroit 's embattled City Council president pro tempore , pleaded guilty Friday to conspiring to commit bribery , a federal court representative in Michigan told CNN . Detroit City Council member , Monica Conyers , admits accepting bribes to sway a $ 1.2 billion contract vote . Conyers , 44 , admitted accepting bribes in exchange for her vote to sway the City Council to approve Synagro Technologies Inc. 's $ 1.2 billion contract in 2007 . It 's unclear when Conyers , the wife of U.S. Rep. John Conyers , began her relationship with Synagro , but court papers say she received money from Synagro until December 2007 . Conyers voted in favor of the wastewater treatment contract on November 20 , 2007 , the same day she received an envelope filled with cash from Detroit businessman Rayford Jackson , court papers say . Jackson pleaded guilty to providing Conyers with the money . He had been a paid consultant of Synagro . On December 4 , 2007 , Conyers received another envelope of cash from Jackson in a McDonald 's parking lot , said Terrence Berg , the U.S. attorney from the eastern district of Michigan . `` She was the swing vote in this deal , '' Berg said . `` She used her power to get the deal done , and she acknowledged that . '' The mood was somber at Conyers ' office on Friday , an official there told CNN . A few office workers cried . They found out about the developments through news reports , said Denise Tolliver , Conyers ' deputy chief of staff . `` We 've been going through this for a while , '' Tolliver said . `` Reporters would ask us questions about anonymous sources , and we just did n't believe them . '' Office workers were preparing for an afternoon meeting with City Council President Kenneth V. Cockrel Jr. later Friday . According to state law , Conyers will have to forfeit her seat , Tolliver said . Cockrel said there 's language in the law that makes it unclear whether she needs to forfeit her seat immediately or after sentencing `` It hurts the City Council 's image , for sure , '' Cockrel said . `` But we need to remember , this is only one member of the council . You ca n't paint the entire council with the same brush . '' For a seven-month period in 2008 , Cockrel replaced former Mayor Kwame Kilpatrick after Kilpatrick pleaded guilty to two counts of obstructing justice . During that time Cockrel terminated the city 's contract with Synagro because of rumors circulating about bribes , he said . Conyers faces a maximum penalty of five years in prison , according to prosecutors . Synagro would not comment on Conyers ' plea , but a spokeswoman said , `` We have cooperated fully with the federal investigation and will continue to do so . ''