A big get with Harvey Weinstein accuser Lauren Sivan wasn’t big enough to pull Megyn Kelly out of her ratings slump.

Her “Megyn Kelly Today” viewership slipped from 0.77 ratings points on Monday to 0.54 ratings points on Tuesday of last week.

“It’s a possible all-time low for ‘Today.’ It may even be lower than her [Fox] cable show. [NBC News president] Noah [Oppenheim] and [NBC News and MSNBC chairman] Andy [Lack] are in big trouble,” a source told us.

Another source added, “That’s a big drop. They have to turn this around.”

Kelly also appeared for the first time on MSNBC earlier this week.

“It’s unthinkable. You don’t see Matt [Lauer] or Savannah [Guthrie] on MSNBC … It’s not a good sign.”

Kelly’s lackluster ratings are also dragging down “Kathie Lee & Hoda,” Page Six reported after Kelly’s hour of “Today” was down 32 percent as compared to a year ago, while “Kathie Lee & Hoda” fell 26 percent, and insiders are blaming that on Kelly’s “weak lead-in.”

But on Friday, an NBC insider insisted: “Megyn’s having a strong week. Her numbers are up double-digits versus last week,” and “NBC News anchors appear frequently on MSNBC.”