Georgia's Republican Senate runoff has become infantile.

The campaign has crawled to an end with a U.S. Chamber of Commerce ad claiming that candidate David Perdue is "crying like a baby." Republican voters will choose today between Perdue and Rep. Jack Kingston.

Babies have been part of the campaign since Perdue aired his first ad in February. It featured crying babies labeled with the names of several primary opponents: Kingston, Rep. Phil Gingrey, and Rep. Paul Broun.

Since then, all of Perdue's ads have featured babies, either sitting on that same floor, or superimposed on the West Lawn of the U.S. Capitol, standing in for his lawmaker opponents.

Even in Perdue's most serious piece of campaign promotional material, a five-minute YouTube video promoting his business career and featuring the candidate speaking in serious tones about the future of the country, the babies show up at 4:12:

When the seven-person primary began, Perdue appeared to be the type of candidate tailor made for the Chamber of Commerce. He is the former CEO of Dollar General, has Fortune 500 leadership on his resume along with a handful of corporate board positions. But Perdue grew testy and walked out of a meeting with the Chamber last fall. This past week, he discussed it on the trail, the Atlanta Journal-Constitution reported.

"I got mad. I walked out of a 60-minute interview in about 10 minutes. There's a rumor going around that I lost my temper. I can confirm for you today that that is true," the paper quoted Perdue as saying.

The Chamber instead endorsed Rep. Jack Kingston and spent at least $2.3 million backing him, according to disclosures to the Federal Election Commission. Perdue and Kingston took first and second place in the May 20 primary, heading to a runoff as neither collected 50 percent of the vote.

During the runoff Perdue kept up the baby theme, with the babies appearing briefly, before a narrator went on to attack Kingston for having served in Congress since 1993:

Kingston has collected the backing not only of the Chamber but of conservative blogger Erick Erickson and former primary foe Karen Handel.