With national and many state polls showing President Obama and Mitt Romney in a very close race, both campaigns are arguing that the polls are concealing their strength. Here's how they're making their cases:

Obama

The Obama campaign's job, The New York Times' Jim Rutenberg reports, is "creating an electorate more favorable to Democrats than most major pollsters have assumed, with percentages of Obama-friendly black, Latino and young voters that rival those of 2008, at least enough to offset the large drop in support among other segments of the population, like independent men." (On Friday, Gallup reported, "The composition of the electorate for the 2012 presidential election is looking quite similar to what it was in 2008 as well as 2004, according to an analysis of the demographics of Gallup's likely voter sample since Oct. 1." But it also suggests the electorate will be much more Republican than four years ago.)

Obama campaign manager Jim Messina told reporters on a conference call Tuesday, "We continue to think it’s going to be a higher percentage of minorities and young people than some are forecasting." He said minority voting would hit "an all-time high," because there are 250,000 more registered black and Latino voters than in 2008. In North Carolina, Messina said, 50 percent more black voters voted in the first five days of early voting than did in 2008.

At The Grio, Addisu Demissie, who was Ohio get-out-the-vote director in 2008, explains how the campaign will turn out black voters who hadn't been reached by Democrats before Obama ran for president. A lot of black voters live in small towns in Republican areas, so they weren't reached by campaign ads or volunteers. 

The 2008 campaign understood that an Obama vote in Lima was just as valuable as one in Cleveland.  And so while we still lost those counties, we lost by less – 20 points instead of 30 in Allen and Butler, 10 instead of 20 in Marion, and so on.

Across a few dozen counties, those numbers add up quickly. So while the three big cities (Cincinnati, Columbus, Cleveland) get all the glory, it may be that the winning margin this time is in the few thousand black voters in cities like Lima (26.4 percent black), Middletown (11.7 percent), and Marion (9.6 percent) that voted for the first time in 2008 and need to be turned out once again. 

The Times reports any extra Obama cash is being used for Spanish-language ads in Nevada and Florida and for get-out-the-vote staff in Iowa and Ohio. Messina told reporters that contrary to Republicans' claims, they aren't just getting people who'd vote for Obama on Election Day to vote for him early. "What early vote does is help us get out low-propensity voters – voters called ‘sporadic’ voters – which broadens are universe and freezes up more get out the vote resources later and especially on Election Day," Messina said.

Romney

"Every cycle, when someone is losing, they claim they are altering the electorate,” Romney political director Rich Beeson told the Times. It's actually Romney voters who are going to turn out in greater numbers than expected in some swing states, Beeson told Politico's Mike Allen. Take Nevada, for example:

The other thing about Nevada to keep in mind is that the rural, the cow counties out there, they vote on Election Day.  So, you've got 11 percent of the vote that's just going to sit there until Election Day, and we're going to win those rurals by big margins. There's a lot of LDS out there, very conservative voters.

Beeson says more Republicans had voted early in Nevada than Democrats two days in a row. Republicans never beat Democrats on that in the state in 2008, he said.

In Iowa, Beeson says, the Obama campaign has "to go into Election Day with a 15 percent partisan advantage on absentee ballots. … Anything over it they'll win; anything under it, we've got a shot at winning..." In Florida, he says Romney has momentum, because "Florida is like an aircraft carrier: Once you start turning it, it's hard to stop, and it's been turning now for about the last 10 days." In Ohio, Beeson says, "We are peeling off an enormous amount of Democrat votes in those coal counties."