You’d need six months to watch every presidential campaign ad

At 30 seconds a spot, and sometimes 60, it would take more than six months to watch all 526,633 presidential election ads that have run on television since the general election began in earnest in early April.

It breaks down to roughly one spot promoting President Barack Obama or attacking Republican challenger Mitt Romney for every spot taking the opposite stance for the Nov. 6 election, according to data compiled by New York-based Kantar Media’s CMAG, which tracks ads on national network, national cable and local broadcast stations.

Of the 526,104 presidential ads supplied by groups that paid for at least 200 such commercials to run from April 10, when Romney effectively clinched his party’s nomination, to Aug. 20, the last day for which data are available, 264,542 came from campaigns or groups that favor Romney and 261,562 came from pro- Obama organizations. That’s a partisan breakdown of 50.3 percent Republican to 49.7 percent Democratic.

While the cumulative total points to partisan parity, it hasn’t been like that for long stretches of the campaign.

Obama had the edge on TV advertising in the spring, followed by Romney and Republican allies having the advantage on television for most of the summer.

The pro-Obama advertising effort is coming overwhelmingly from the president’s own campaign, which has aired more than 10 times as many ads as an allied super-political action committee, Priorities USA Action, which is headed by former Obama White House aides.

The push to elect Romney is far more reliant on outside groups, including super-political action committees and 501c nonprofit groups that are focusing their ads on attacking Obama. Crossroads GPS, a nonprofit founded with the help of Republican strategist Karl Rove, and Restore Our Future, a pro-Romney super-PAC, have together supplied more ads than Romney’s campaign.

While the two parties are at cumulative parity in TV advertising for the presidential race, the Republican side is pulling ahead as the campaign enters its final months.

In the 14-day period ending Aug. 20, the pro-Romney side aired 52,637 ads and the pro-Obama side ran 38,706 spots, a 58 percent to 42 percent split, CMAG data show.