The 8 p.m. buys on CBS and NBC may be the last of what has been a relatively tepid season of campaign buys on network TV during this race, though Obama's campaign also is in discussions with ABC and Fox to make it a true prime-time roadblock.
To date, both Obama's and John McCain's campaigns have utilized network TV buys only sparingly - mainly buys on NBC's coverage of the 2008 Beijing Olympic Games.
Network TV was not expected to be a big factor coming into this presidential race, as the medium has been waning as a platform for the past 20 years as candidates sort to geographically target their messages with spot TV and radio and local cable TV buys, and especially as they've begun embracing online media and search advertising.
The last time a presidential candidate purchased a half-hour of network prime-time was when H. Ross Perot's Independent party campaign did in 1992. Typically, those buys have been based around plain-talking addresses to the American people. The last time a high production value half-hour ad was produced was in 1984, when Ronald Reagan's Tuesday Team created the apocryphal "Prouder, Stronger, Better" ad - also known for its memorable "It's morning again in America" line. The long-form version of that spot, which was written and produced by legendary Madison Avenue ad man Phil Dusenberry, and narrated by Hal Riney, ran in its entirety only during the Republican National Convention, but short-form 30-second versions were largely credited with helping to reelect Reagan.
Interestingly, Obama's Wednesday night half-hour prime-time special will air a night before one of "SNL's" Thursday night specials, which have been lampooning both candidate's campaigns leading up to the election.