Tom Kean Jr, a Republican congressman who disappeared from the Capitol for nearly four months with little explanation, re-emerged on Tuesday and said that he was absent while dealing with depression.

“Several months ago, due to health concerns, I entered the hospital for some testing. I did not believe that this would result in a long-term stay. I was given the diagnosis of depression,” Kean said in a speech on the floor of the House Tuesday morning.

Kean, who represents a swing district in New Jersey, had last voted on 5 March before disappearing, with his office in late April saying only that he was dealing with a “personal health matter” and would be back “soon”.

In the first comments he has made since returning to Washington DC, the congressman did not say directly why he had kept his mental health struggles private, but described himself as a “private person by nature”, and indicated that the treatment for depression took longer than expected.