The pleas come with alarming regularity -- sometimes from senior aides, others from Vice President Joe Biden and even from President Obama himself: Donate now or we'll be outspent.
But for all the alarm that the Romney campaign and their outside allies would raise hundreds of millions of dollars from a small group of wealthy millionaires to drown out Obama's message on the airwaves, that hasn't happened.
In fact, the Obama campaign has actually dominated the airwaves where it matters -- in key battle ground states across the country.
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A recent report by the Wesleyan Media Project found that following the conventions, the Obama campaign and its allies had actually aired more ads in battleground states than Romney and his allies.
"I do think we all expected that pro-Romney ads would be dominating the air wave and that's certainly not what we've seen in the last five weeks," said Erika Franklin Fowler, co-director of the Wesleyan Media Project.
So far this cycle, the Obama campaign has raised more money overall -- $432 million to Romney's $279 million, according to OpenSecrets.org.
And in September, it raised more than any other presidential candidate in history in a single month -- a whopping $181 million. The Romney campaign has not released its September fundraising totals.
Still, on Monday, Obama campaign senior advisor David Axelrod emailed supporters asking for donations because Romney's allies "are trying to buy this election."
The Obama campaign argues that its successful fundraising from traditional donors doesn't mean they won't be eventually outgunned. The Romney campaign may not be spending as much on ads, but his outside allies have and they can raise unlimited sums of money from very wealthy donors.
Romney has been aided by his allies in making up the spending difference between his campaign and Obama's.
According to the Washington Post, since mid-April when Romney essentially cinched the Republican Presidential nomination, he and his allies have spent $223 million on ads, compared to $206 million by Obama and his allies.
Of the top 15 groups spending the most on ads on the airwaves during the general election, 11 support Mitt Romney.
And last week, the Romney-allied super PAC American Crossroads, along with its sister group Crossroads GPS pledged $16 million in ads on radio and TV targeting the president, making it their largest ad-buy so far this cycle.
But Romney's outside support may actually be one of the factors explaining Obama's dominance on the airwaves.
Due to Federal Communications Commission regulations, political campaigns can put more ads on the airwaves for their money than outside groups.
"If you add up all the dollars, pro-Romney groups had been spending more in the last few weeks but they were getting fewer ads," Fowler said.
Fowler's study concluded that contrary to popular belief, the Obama campaign had aired more ads than Romney in 14 out of 15 top battleground state markets. In that 15th market -- Las Vegas -- Obama was outmatched only because outside groups heavily backed their ads with cash.
With fewer than 28 days remaining before the election, millions more in ad money is likely to flood the airwaves and there is still plenty of time for the balance of power on the airwaves to shift dramatically.
But there's reason to believe the trends will continue to favor Obama.
Outside groups will likely continue to back Romney, but their spending won't get them as far as the Obama campaign's money will.
And at least as of the end of August, the Obama campaign was left with $89 million cash in the bank to Romney's $50 million.
Obama has also been more strategic about where his campaign spends his money -- sometimes aiming for programs that are cheaper, like the ones that air during the day -- in order to target specific demographics, Fowler said.
"The campaign is being incredibly efficient in the way they've gone about spending on ads," Fowler said. "Even within markets you're seeing some of the targeting in the program where the campaign is spending a large amount of their dollars."
The "micro targeting" of television ads that the Obama campaign utilizes aggressively is actually a strategy that Republicans pioneered in previous elections. But the Romney campaign has been slow to utilize it so far in this election.
"One of the puzzling things is why Romney's campaign isn't using it more frequently," Fowler said.