What does 'fumble' in the passage means:

Directions: Read the following passage carefully and answer the questions that follow:

Even though every interview is a vital occasion, it should notbe taken seriously. Most of the candidates fell extremely self-conscious and nervous a little before the interview. They brood much over the occasion, trying to calculate their chances of success. All this makes them a little abnormal and they are unable to display their natural qualities before the board. They stammer and fumble in speech, look pale and scared and behave even awkwardly and shabbily in and out of the interview room. It is, therefore, very essential that the interviewees should keep their mind off the experience they going to pass through. They must face the occasion as stoically and realistically as possible. The motto of every interviewee should be “Hope for the best but expect the worst.”