Mitt Romney, Clint Eastwood and the empty chair drove Fox News Channel to the top of the TV rankings on Thursday.

The cabler’s coverage of the final night of the Republican National Convention surged to 9.1 million viewers in the 10-11 p.m. hour that featured the address of presidential nominee Romney and the surreal theater of Eastwood conversing with a chair meant to symbolize President Obama. That hour ranked higher in total viewers than anything else in primetime, broadcast or cable, on Thursday.

Nielsen reported that 30.3 million viewers tuned in to live coverage of the confab from 10-11:15 p.m. across the Big Three nets and Big Three news cablers, as well as Univision, Telemundo, Mun2, PBS, CNBC and Current. That was down 22% from the 38.9 million who tuned in to the closing night of the 2008 Republican hootenanny (which was not covered by CNBC, Current or Mun2).

ABC was second to Fox News in the 10 p.m. hour with 4.4 million viewers, followed by NBC (3.8 mil), CBS (3.7 mil), CNN (2.3 mil) and MSNBC (1.9 mil). Fox News noted that it was down only 2% versus the comparable hour from the 2008 GOP convention, while other nets were off by double digits.

For all of primetime, Fox News doubled its cable competitors combined, with an average of 5.9 million viewers (down 6% from ’08) to MSNBC’s 1.4 million (down 19%) and CNN’s 1.3 million (down 59%).

Once again, the aud for the political powwow was largely an older crowd. According to Nielsen, 17.5 million of the viewers in the 10-11:15 p.m. slot were 55-plus, with only 3.2 million falling into the 18-34 range and 8.3 million in the 35-54 demo.