Fortenberry said in a statement that he couldn't serve you effectively due to his current circumstances.
McCarthy suggested that Fortenberry should resign from Congress and that he would talk to the congressman that day.
McCarthy told reporters on the final day of the House GOP retreat that when someone is convicted, it's time to resign. Many of Fortenberry's colleagues were shocked by the news and cited his commitment to his faith.
Pelosi called on Fortenberry to resign.
Fortenberry's conviction represents a betrayal of the public trust and confidence in his ability to serve. She said that no one is above the law.
A federal jury found Fortenberry guilty on Thursday of three felonies after misleading federal investigators about his knowledge of campaign donations made with funds from a foreign national.
Fortenberry lied to investigators when he denied knowing that Gilbert Chagoury, a wealthy businessman who lives in France, donated $30,000 to his campaign through a middleman.
Fortenberry, who faces a possible prison sentence of up to five years on each count as well as fines, denied the charges and has said he plans to appeal. He is the first member of Congress to be convicted while in office.
Fortenberry was indicted by a grand jury on charges of making false statements and scheming to deceive federal agencies, and he stepped down from his position on the House Appropriations Committee.
Fortenberry said in January that he would run for reelection. Many prominent Nebraska Republicans moved their support to state Sen. Mike Flood, who had already jumped into a potential primary for the state's 1st Congressional District amid concerns that Fortenberry's conviction could cost the party a GOP seat.
The district includes a stretch of rural eastern Nebraska but also captures liberal-leaning Lincoln and grew more Democratic in recent years. It is not yet clear how Fortenberry's resignation and the resulting special election will affect the district.
Nebraska Democratic Party Chair Jane Kleeb said in a statement that Democrats are prepared to run and win in order to address the issues Nebraskans care about.
Fortenberry's decision to resign from his position was praised by Rep. Don bacon, who hails from the same state.
Sarah Ferris, Josh Gerstein and Myah Ward contributed to the report.