Exclusive: Some staffers at MSNBC have floated the notion of a schedule shift that would completely overhaul the network's primetime lineup, TVNewser has learned.

Nothing is set in stone, but the ideas are on the table. Imagine Tucker Carlson at 8pm, a courts and crime show at 9pm, Joe in Scarborough Country at 10pm, and Countdown with Keith Olbermann at 11pm. It's just one of several scenarios that may perk executive ears, according to sources.

A couple of things are certain: The network is very excited about Carlson's show, which is very tentatively slated to premiere in the next month. Pilot programs are underway. Perhaps it would fare better at 8pm, against O'Reilly and Zahn, than it would at 9pm, against King, Hannity and Colmes. (Is it a more natural lead-in after Hardball?)

The network is considering a Nancy Grace clone at 9pm -- not unlike what Dan Abrams has been doing, plugging the time slot vacated by Deborah Norville in January. Lisa Daniels is a rising star at MSNBC, and some insiders believe she should have a shot at primetime. Perhaps the Friday at 4pm show was a tryout. Crime at 9 would serve as counterprogramming. (Plus, you've got Grace at 8 and Greta at 10.)

Some people believe Countdown would work well later in the evening. It's especially attractive to the key 25-54 demographic. Again: The changes are by no means guaranteed. But there's a buzz in Secaucus. Let's see if it gets louder...