Kennedy Jr. on Thursday struggled to answer questions about Medicare, refused to rule out a debunked link between autism and vaccines, and said he would entertain conspiracy theories about the Sept. 11,

For Sen. Maggie Hassan, the falsehoods that have been spread about any link between vaccines and autism are beyond the pale—and hit close to home. The Democratic senator from New Hampshire on Thursday confronted one of the most influential disseminators of this conspiracy theory,

The New Hampshire Democrat described raising a son with severe cerebral palsy and ripped Kennedy for "relitigating" settled science on autism.