It looks like CBS’s choice of Norah O’Donnell for the Evening News might not have been a good one.

CBS has been in last place in the evening news race for years, but it is getting even worse under O’Donnell.

The New York Post writes that in the last week alone, O’Donnell’s total viewers plunged 17 percent to 5.1 million, according to Nielsen. Among viewers in the crucial demographic ages 25 to 54 that’s coveted by advertisers, the drop was a heart-stopping 25 percent.

The slide has steadily accelerated during the past month, with weekly ratings in the key age group falling between 20 and 29 percent versus a year ago. That’s far steeper than the single-digit drops during the year-and-a-half tenure of her predecessor Jeff Glor, who was pulling down $2 million a year, according to a source.

“This is definitely unusual,” said television analyst Andrew Tyndall. “I don’t see any prospects of ‘CBS Evening News’ getting out of third place, but an honorable third versus a dismal third is possible.”

Somewhere, Jeff Glor has a smile on his face.