Anderson Cooper 360 may have had a new format at 10 PM on CNN this week, but it didn’t have many viewers. The new panel-style show that ran Monday-Thursday was the least-watched broadcast on cable news in the time slot and the second-lowest in the adults 25-54 demographic. The show had a coatless Cooper debating with permanent panelists Amy Holmes of The Blaze, CNN’s Jeffery Tobin and Christiane Amanpour, plus Andrew Sullivan, Anthony Bourdain, former White House Press Secretary Ari Fleisher, and ex-Desperate Housewives star Eva Longoria joining on separate days. On average over the week, the revamped AC 360 garnered 503,000 viewers, and 167,000 in the demo. In terms of viewership, the latest experiment of the Jeff Zucker regime was behind Fox News’ On The Record (1.436 million viewers/206,000 in demo), MSNBC’s Last Word With Lawrence O’Donnell (654,000 viewers/146,000 in demo) and CNN sister station HLN’s After Dark (588,000 viewers/194,000 in demo), according to Nielsen. The temporary new AC 360 had one win — beating Last Word in adults 25-54 — but that pales when compared to the double-digit drop the show saw compared with the week before: From Monday-Thursday, AC 360 down 32% in viewership and 34% in the demo from the 10 PM edition of AC 360’s performance April 22-25.

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The best viewership nights for the 10 PM AC 360 were May 1 and May 2, when it pulled in an audience of 562,000. Its best demo day was Monday, when it got 235,000 among the 25-54s. That was still behind the demo high of FNC’s Greta Van Susteren on April 30 (237,000) and well behind the 1.6 million On The Record pulled in May 1, its best showing of the week.

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With the exception of breaking news — like the week of the Boston Marathon bombing and manhunt — a repeat of the 8 PM AC 360 traditionally sat in in the 10 PM slot. In what could be called a hollow victory, the panel experiment was up 21% in viewership and 24% among adults 25-54 from the comparable week last year. However, April 2012 was CNN’s lowest-rated month in over a decade. The panel show this week did beat the previous ill-rated panel experiment (Get To) The Point, which dismally sat in the slot during the week of April 1-4.

No word yet what new roll of the dice is coming for the 10 PM slot next at CNN.