ABC News' Michael Falcone reports:

Mitt Romney and his Republican allies have struck a tone of exasperation about President Obama's use of Big Bird as a campaign issue ever since Romney invoked the giant, yellow "Sesame Street" character at last week's debate in Denver.

And although Obama has let the Big Bird attacks take flight on the campaign trail, and most recently, in a tongue-in-cheek television ad, it's also worth noting how frequently Romney has deployed the popular Sesame Street character throughout the 2012 election.

"You have to scratch your head when the President spends the last week talking about saving Big Bird," Romney said on Tuesday in Van Meter, Iowa.

Earlier in the day, Romney campaign spokesman Kevin Madden also railed against the president.

"Right now you've got 23 million American's struggling to find work. You've got household incomes going down. You've got a federal deficit - federal debt that's now over 16 trillion dollars," Madden told reporters. "I just find it troubling that the president's message - the president's focus - 28 days from election day is Big Bird."

The Republican National Committee is referring to the kerfuffle as the "Big Bird Backfire." The RNC even used "Sesame Street's" Count von Count in their pushback against Obama on Tuesday.

But back as far back as December 28, 2011, in Clinton, Iowa, Romney started talking tough about the giant yellow bird.

"You might say, 'I like the National Endowment for the Arts.' I do. I like PBS. We subsidize PBS. Look, I'm going to stop that. I'm going to say, 'PBS is going to have to have advertisements,'" Romney told a crowd at a deli in the Eastern Iowa town. "We're not going to kill Big Bird, but Big Bird's going to have to have advertisements, all right? And we're going to have endowments for the arts and humanities but they're going to be paid for by private charity not by taxpayers - or by borrowers."

President Obama has been mocking Romney on the stump for declaring at last week's debate, "I'm going to stop the subsidy to PBS. I'm going to stop other things. I like PBS, I love Big Bird."

At Cleveland State University last week, Obama joked that his Republican opponent was "finally getting tough on Big Bird."

"Governor Romney is going to let Wall Street run wild again, but he's going to bring the hammer down on 'Sesame Street,'" Obama said.

And Obama campaign spokeswoman Lis Smith said in a statement on Tuesday, "If anyone should be scratching their heads, it's the American people when Mitt Romney says that he'll reduce the deficit and pay for $5 trillion in tax cuts for the wealthiest Americans by getting rid of PBS and Big Bird, which make up 1/10,000th of the federal budget. That's not a serious deficit reduction plan - it's a joke."

Here's a sampling of some of Romney's other Big Bird shout-outs during the election cycle:

Mitt Romney on Sean Hannity's radio program (March 15, 2012):

"We're going to have to stop some things we also like. I mean, I like PBS, for instance. I like my grandkids being able to see Bert and Ernie and Big Bird, but I'm not willing to borrow money from China so that PBS doesn't have to run advertising."

Mitt Romney in Liberty, Mo. (March 13, 2012):

"I like PBS, but we borrow money so that PBS doesn't have to show advertising to our kids. Well, Big Bird's going to have to get used to Kellogg's Corn Flakes because we're going to have to have advertising or bigger donations. We just can't keep on borrowing money and keep passing on those burdens to our kids."

Mitt Romney in Flint, Mich. (Feb. 25, 2012):

"We borrow money so that when you were little you watched Big Bird an Bert and Ernie, you didn't have to see any advertisements. I'm not willing to borrow money from other people to do that, you're going to have to get used to Big Bird and Corn Flakes on the same program. We're not going to borrow money from people to do things that we don't have to do and so number one I'm going to have to get rid of some programs and cut some programs."

Mitt Romney in Lansing, Mich. (Feb. 25, 2012):

"We send money every year to pay for PBS so they don't have to have advertising on Sesame Street. I like Sesame Street, but I am willing to have Big Bird look at cornflakes from time to time, okay? I just think we shouldn't borrow money to pay for that."

Mitt Romney in West Palm Beach, Fla. (Jan. 12, 2012):

"I like PBS. I like Bert and Ernie and Big Bird, but you know we get money from the government so they don't have to have advertising. I'm afraid Big Bird is going to have to get used to Kellogg's Corn Flakes. We can't just keep borrowing and borrowing and borrowing like there is no tomorrow."