Washington DC - Congressman Tom Kean Jr. returned to Washington on Tuesday after a mysterious months-long absence – revealing that he had been hospitalized for depression.

Kean, a vulnerable New Jersey Republican seeking a third term in November's midterm elections, had been away from the House of Representatives for more than 100 days, missing dozens of votes as his party tried to steer legislation through a narrowly divided chamber.

"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 House floor.

"Now, when people hear the word depression, many people think simply feel it means feeling sad, but depression is so much more than that. It is physical, it is emotional, and until you experience it yourself, it is difficult to fully understand how powerful this illness can be."

Donald Trump Trump urges Congress to end birthright citizenship after Supreme Court rejection

The 57-year-old said doctors advised him to remain in the hospital, and that while he had initially expected to return within weeks, his recovery took longer than anticipated.

His absence had fueled speculation in New Jersey and Washington after his office said only that he was dealing with a personal medical issue and would make a full recovery.

The son of former New Jersey governor Tom Kean Sr., the congressman represents one of the most competitive Republican-held districts in the country.

The prolonged absence complicated life for Republican House Speaker Mike Johnson, whose party has only a slim majority and can afford few defections or missing votes on partisan legislation.

Kean said he was now "healthier, stronger, and excited to return to the work that I love" – and urged others struggling with depression to seek help.

"Asking for help is not a weakness," Kean said. "It is a strength."