Jimmy Kimmel returns from paternity leave to discuss health care with Sen. Bill Cassidy

Kimmel's plea for people with pre-existing conditions received many responses.

One of Kimmel's guests will be Republican Sen. Bill Cassidy of Louisiana.

Last week, Cassidy, who is also a physician, coined the term "the Jimmy Kimmel test" while discussing a new standard for health care reform.

Later, he tweeted, "Senate must fulfill #KimmelTest. Cover for pre-existing conditions, adequate coverage. But in a fiscally conservative way that lowers cost."

Cassidy's remarks came just days after Kimmel delivered an emotional opening monologue last Monday about his newborn son William, who was born with a heart defect that required surgery three days after he was born. He will have to undergo another open-heart procedure within the next three to six months.

During his monologue, Kimmel made a plea for politicians, both Republican and Democrat, to make sure all Americans have access to medical care, especially those with pre-existing health conditions.

"Well said, Jimmy. That's exactly why we fought so hard for the ACA, and why we need to protect it for kids like Billy. And congratulations!" Obama wrote.