The 79-year-old president made the blunder at a conference on hunger, nutrition and health.
Joe Biden thanked those for who played a part in the bill including Jackie Walorski.
The president looked round the room in Washington and said: "Jackie, are you here? Where's Jackie? She must not be here" on Wednesday.
White House press secretary Karine Jean-Pierre field a flurry of questions during the press briefing saying that Ms Walorski was "top of mind" for Mr Biden –as he was due to meet the congresswomen’s family to sign a bill renaming a veterans' affairs clinic in Indiana after her.
She did not acknowledge that the president had misspoken saying "All of you may have views on how I am answering it, but I'm answering the question to the way that he saw it and to the way that we see it."
Ms Walorski's brother, Keith told the New York Post that President Biden was doing the best he could and that he was not angry about the gaffe stating "Yeah it was a big mess-up today. Inexcusable? No. Unforgivable? No. I'm not gonna hold it against him. I just feel sorry for him."
He added: Mr Biden is "doing the best he can do with what he's got right now"
President Biden had called Ms Walorski's family to offer his condolences after she died.