9:19 PM: Only a few minutes in, but man, Newt’s on his game tonight. Even seems lighter on his feet somehow. Romney’s certainly on message too, consistently. But he hasn’t really landed a punch.

9:21 PM: This is really brilliant maneuver on Newt’s part, managing to whack Mitt on 15% and somehow sort of do it from the right.

9:23 PM: It was an interesting thing when Mitt pointed out that under Newt’s plan he’d have paid 0% rather than 15%. Good point. But just not one Mitt can do anything with. It’s basically saying heck with Newt’s policy my rate would be even more ridiculous than it is now! That doesn’t work.

9:28 PM: Okay, I think Mitt’s got his ducks in a row on ‘historian’.

9:30 PM: Entities!!!!

9:30 PM: Mitt’s finally getting under Newt’s skin. Reminds me of Mitt’s glory days decapitating Rick Perry.

Get the very latest updates on tonight’s debate at TPMLiveWire — the quotes, the video, everything.

9:02 PM: Fight Club.

9:04 PM: About as good an answer as Newt could give to that question. In fairness to Newt, that was at least the trigger for Newt leaving the Speakership — he took the hit for losing the 1998 mid-term election.

9:06 PM: “resigned in disgrace” … “influence peddler” … Now we’re talking.

9:08 PM: Okay, don’t think this debate is going to disappoint.

9:10 PM: Can’t believe Newt’s going with the historian line. That said, Mitt give Newt an opening by conflating the ethics thing and Gingrich’s resignation a couple years later. Not actually related.

9:13 PM: I haven’t seen it that much remarked about how Santorum is now running consistently to the left of the other candidates on economic issues. Not really in substance in policy terms. And it doesn’t take much with this set of candidates. But still, clearly a considered decision.

Tonight is the 18th GOP presidential debate of the 2012 cycle, and first in which Mitt Romney is likely to go ont he attack against Newt Gingrich. Watch live.