PHILADELPHIA (CBS) - Longtime Pennsylvania Senator Arlen Specter is seriously ill, CNN reported Monday.

Specter, 82, was diagnosed about six weeks ago with a new form of cancer, the specifics of which are being kept private by his family, the CNN source said.

Specter reportedly had a “big flare up” of the disease Monday night.

Specter has overcome numerous serious illnesses over the past two decades, including a brain tumor and non-Hodgkin lymphoma.

He served in the United States Senate for 30 years. He was a Republican from 1965 until 2009, when he switched to the Democratic Party. He was defeated in the 2010 Pennsylvania Democratic Primary by Representative Joe Sestak.