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.”…

“Of course it’s important to have that money advantage, but what has to be unsettling for the Romney team is that they’ve not found a message that will break through in the battleground states,” said Republican strategist Ford O’Connell. “I don’t think the money’s going to dry up. I don’t think that’s a concern right now. I think their biggest concern is how to win Ohio and Virginia.”