Ratings Chart Attack!

“The Big Bang Theory” received a big bump last night, as the CBS sitcom posted its highest ratings of the season and its largest audience ever, while “Saturday Night Live’s” pre-election special lifted NBC to a nightly win.

“Theory” drew a 3.8 rating/10 share in the 18- to 49-year-old demographic, according to preliminary Nielsen Media Research data. The show grew 9% from its last original episode, tying its high in the demo.

“Theory” also brought in 9.9 million, a series high.

“How I Met Your Mother” (4.1/10, 9.6 million) also brought home a season high, increasing one-tenth of a percentage point from its last original episode.

While the front end of CBS’ lineup enjoyed gains, the rest of the night declined as “Two and a Half Men” (4.6/10, 12.8 million), “Worst Week” (2.7/6, 8.4 million) and “CSI: Miami” (3.6/9, 12.7 million) dipped 10%, 16% and 5%, respectively.

This is the sixth weekly decline for “Miami.” The show hasn’t posted a gain in original telecasts this season.

CBS took second place for the night with a 3.7/9; it was third in total viewers with 11 million.

NBC stayed afloat on Monday with its two-hour “Saturday Night Live Presidential Bash 2008” (5.6/13). Despite declining 5% from “SNL’s” 2004 election special, the show was the highest-rated program of the night.

“Deal or No Deal” (2.0/5) celebrated its 200th episode last night. “Deal’s” performance dropped 23% from “Chuck’s” last week in the time period, while “SNL” improved ratings by 81% versus “Heroes” and “My Own Worst Enemy” last Monday.

NBC ended the night with a 4.4/10.

ABC’s “Dancing With the Stars” (3.9/9) tripped 7% from last week, posting its lowest regularly scheduled performance show ever. “Samantha Who?” (2.7/6) and “Boston Legal” (2.0/5) were on par.

ABC placed third with a 3.1/7 for the night.

“Terminator: The Sarah Connor Chronicles” (2.0/5) and “Prison Break” (2.1/5) were essentially flat with their previous showings. Fox took fourth with a 2.0/5.

The CW placed fifth with a 1.6/4, as “Gossip Girl” (1.6/4) rose 11% in the network’s key demo of women 18-34 with a 3.9/10. “One Tree Hill” (1.6/4) declined slightly from last week, moving down one-tenth of a ratings point.