SIOUX CITY | Republican presidential candidate Mitt Romney used a big push of television campaign ads in Sioux City and Iowa over the final month in the failed attempt to unseat President Barack Obama.

From Oct. 6 through Election Day, Romney and supporting political action committees spent $1,653,999 on Sioux City stations, while Obama and PAC counterparts spent $1,175,376, according to new data compiled by the Journal.

That turned around the spending trend over the prior six months where Obama and PACs outspent Romney and groups that supported Romney, with $2,553,275 compared to $1,970,646. Those ads aired from March 26 through Oct. 5 on Sioux City stations.

The $2.83 million spent on ads by Romney, Obama and the PACs showed a huge final month splurge, since $4.5 million had been spent over the prior five months.

"We were all overwhelmed by the onslaught," said Morningside College Political Science Professor Patrick McKinlay.

As Iowa hung in as a swing state with competitive polling through October, the two candidates knew they had to focus on the Hawkeye state, University of Iowa Political Science Professor Tim Hagle said. That became increasingly true for Romney, as polling showed he had lost ground in other battleground states, McKinlay added.

"As the prospects for the Romney campaign narrowed, they realized Iowa was a must-win," McKinlay said.

Romney and supporting PACS pushed hard not only in Sioux City, but in all Iowa television markets. The Romney campaign groups outspent Obama and supporting PACs in all eight Iowa markets after Oct. 5, spending a combined $21.45 million compared to $11.88 million for Obama and his groups. All that money was turned into 112,522 ads that aired on all Iowa stations combined over the last month.

Obama ultimately won the state of Iowa, and the presidency by amassing 332 electoral votes.

McKinlay said politicos should mull the effectiveness of television ads in the aftermath of the election. He said Obama worked a coordinated grassroots get-out-the-vote plan built over four years, so campaign ads aren't remotely a magic bullet to deliver potential voters.

"Is there a point where there are diminishing returns on ads? You've got to wonder whether that many ad buys really gets you that many more voters," McKinlay said.

Hagle said Republicans in particular have to be mulling how the campaign strategies played out, since they figured Romney had a chance to win in a year incumbent Obama was running during sluggish economic times.

"These kinds of things sometimes fall by the wayside if you've got a good ad. A good ad can be one that helps you, although usually it is one that is negative. People always complain about negative ads, but guess what -- they work," Hagle said.