Will ad fatigue mute GOP's late barrage? (CBS News) Republicans' expected financial advantage in the presidential campaign's final weeks may not pay the dividends they had once hoped for. Throughout the spring and early-summer months, Mitt Romney bided his time as President Obama's re-election team poured its resources into a series of early advertising blitzes intended to define their opponent as a hard-hearted opportunist. As the former Massachusetts governor worked to replenish his own coffers after a draining primary fight, his campaign pointed to evidence that Obama's assault on Romney's business background was not moving the needle, and GOP strategists conveyed private assurances to donors that the tide would turn once the financial playing field leveled off in the fall. "Over 75 percent of the advertising the Obama campaign has run has been negative, anti-Romney ads, with at least 14 separate negative ads," the Romney campaign noted in a publicly issued July 8 memo. ." . . Yet, despite all of the negative advertising from the Obama campaign, polling numbers are exactly where they were before they started this onslaught. That may have been true then, but there is now general agreement on both sides that the early Obama push was effective in negatively defining Romney. Less certain is whether the post-Labor Day fundraising sprint, when the Romney camp's prudence in conserving its resources earlier was supposed to pay off, will reap similar rewards for the Republican. It apparently hasn't done so, though not because of any slide in Romney's vaunted fundraising prowess. On the contrary, his campaign and aligned Republican committees raised an impressive $111.6 million in August, and Romney fundraising officials told major donors at the party convention in Tampa last month that they expected an even bigger haul in September, according to a GOP source. But the Obama campaign and Democratic committees upped the ante last month by narrowly outraising their counterparts for the first time since April and have enjoyed an overall advantage in the race thus far of more than $100 million, according to a recent Reuters analysis that did not include money raised by outside groups. When super PACs and other advocacy groups are factored into the equation, Romney and his allies are still expected to have a significant financial edge in the final seven weeks of the campaign, the first one since the Watergate era is which both candidates declined public financing, thus enabling the spending binge. But with so much money targeting relatively few voters in key swing states, there is growing concern among Republicans that the advantage Romney is expected to have when those voters historically tune into the race may not be so significant after all. In other words, will the undecided simply tune out the increasingly inescapable noise from the late campaign ad barrage? "We're sort of in uncharted territory here," a senior Romney adviser said. Regardless of a point of diminishing returns, we're not going to be outspent by an incumbent president, and I think that's important. At what point it becomes a tipping point, I don't know, but we're not going to be outspent like John McCain was, three to one, in 2008.