ABC’s “Commander in Chief” is looking more and more like a one-term show after last week’s seg fell to its lowest-yet approval ratings in the Nielsen polls.

The once-promising rookie drama, which peaked with its second episode last fall, has faded considerably since. Its move to Thursday following an 11-week hiatus has done nothing to reverse the downward momentum.

After a soft but passable Thursday start on April 13 (2.4 rating/7 share in adults 18-49, 8.20 million viewers overall), “Commander in Chief” declined 13% in the key demo last week (2.1/6 in 18-49, 7.69m) and finished deep in third place — even though its “American Inventor” lead-in rose 14% week to week (3.3 vs. 2.9).

It’s not that the competition was that intense, with NBC’s “ER” a repeat (2.5/7, 6.20m) and CBS’ “Without a Trace” on the low end of its firstrun range (5.0/14, 16.93m), according to Nielsen figures.

Last fall, opposite competition that included Fox’s “House,” the Geena Davis starrer “Commander” averaged a 4.5 rating/11 share in 18-49 and 16.5 million viewers overall with its first four episodes — making it the season’s No. 1 new drama in the early going.

ABC would very much like to bring back one of its first-year dramas next season, but none has really stuck with auds. “Commander” and Wednesday’s “Invasion” rep its best shots.

This week becomes key for “Commander” as well as “Invasion,” which returned last week after a month’s layoff to nothing-special numbers (2.6/7, 7.11m), although it does seem to have a little buzz building toward its May 17 finale.

A lot depends on how ABC execs feel the shows are progressing creatively. “Commander” has been through a lot in its first term, changing showrunners twice since its bow last September.

The Alphabet will announce its fall sked next month.

One rookie series that is looking good after a move to Thursday is the WB’s “Supernatural” (1.9/5 in 18-49, 3.99m) following “Smallville” (1.9/6, 4.41m). Spooky skein, which began the season on Tuesday, retained 100% of its 18-49 lead-in from “Smallville” and 86% in 18-34 (1.9/6 vs. 2.2/8) — its best Thursday scores to date.

Combo would seem to be a good bet to return in tandem on the new CW sked next fall.