Even with “CSI” in repeat, CBS rolled to another Thursday victory in key demos this week, while ABC’s “Commander in Chief” struggles to find an audience on its new night.

According to preliminary nationals from Nielsen, “Survivor: Exile Island” (5.4 rating/17 share in adults 18-49, 16.3 million viewers overall), a repeat “CSI” (5.4/15 in 18-49, 18.7 million viewers overall) and a new “Without a Trace” (5/14 in 18-49, 16.7 million viewers overall) each led their hours in all key categories.

At ABC, “Commander in Chief” (2.1/6 in 18-49, 7.7 million viewers overall) declined more than 10% from its mediocre time-period premiere one week earlier — lagging in demos both “Without a Trace” and a repeat “ER” on NBC (2.5/7 in 18-49, 6.2 million viewers overall). The Alphabet started slowly at 8 with an “American Inventor” recap before moving up to second at 9 with a new installment of the unscripted series (3.2/9, 8.4 million viewers overall), which was up slightly week to week.

NBC, which had scrapped “Celebrity Cooking Showdown” from its sked due to low ratings, aired all repeats and was paced by “My Name is Earl” (3.3/9 in 18-49, 7.7 million viewers overall) and “The Office” (3/8 in 18-49, 6.1 million viewers overall).

Fox was led at 9 by “The OC” (2.5/7 in 18-49, 7.7 million viewers overall).

Preliminary 18-49 averages for the night: CBS, 5.3/15; NBC, 2.6/7; ABC, 2.4/7; Fox, 2.2/7; WB, 1.8/5; UPN, 1.1/3.

In total viewers: CBS, 17.2 million; ABC, 7.3 million; NBC, 6 million; Fox, 4.7 million; WB, 3.9 million; UPN, 2.7 million.