While Mitt Romney has attributed his defeat, in part, to "gifts" President Obama was able to shower on key constituencies, a Republican National Committee report on the election points to other reasons -- like changing demographics, Hurricane Sandy, George W. Bush, and the failure to win over the middle class.

This RNC report of exit poll data, which NBC News has obtained and which RNC Chair Reince Priebus presented to GOP senators on Wednesday, states that "demographic change" in the United States "is real." It notes that the white share of the electorate has declined from 81% in 2000 to 72% in 2008. And it points out that "3 in 10 voters will be minorities in 2016."

(Click here to see the full report.)

In addition, the report (which Politico also has written about) includes data from the exit poll showing that voters -- by a 53%-to-38% margin -- blamed Bush for the state of the economy instead of Obama.

It also observes that Obama's response to Hurricane Sandy "provided a bump" to the president, with 42% saying it was either the "most important" or "an important" factor in their vote. Obama won those voters by more than a 2-to-1 margin

And the presentation observes that 44% of voters believed Obama's policies favored the middle class, versus 34% who said that of Romney's policies.

But the RNC report also notes the positives from the election:

-- Romney outperformed John McCain from 2008, especially in battleground states

-- Fewer than a combined 400,000 votes in Florida, New Hampshire, Ohio, and Virginia separated Romney from the presidency (though even fewer than that amount separated Al Gore and John Kerry from the presidency, too)

-- And Romney improved among whites and independents from 2004 and 2008.

At the end of this presentation, the RNC says it will conduct a fuller "deep dive" report into what worked in 2012 and what didn't. That will include conducting a post-election survey, meetings with party leaders, and getting feedback from volunteers.