There was zero alternative media back then like internet, podcasts or even talk radio. Well, they had some talk radio but it was predominantly liberal, at least in Boston (Jerry Williams, Larry Glick).
So the media narrative that entire election season was that Carter would handily win re-election. The attempted rescue that April of the Iran hostages failed but according to the media, the fact that Carter even tried, would ensure his re-election.
Also, we had John Anderson, a Republican turned Independent, running as a third party candidate and the conventional wisdom had it that he would offer the GOP establishment an alternative to the "reckless cowboy" Reagan and thus split the Republican vote that would allow Carter to easily cruise to victory.
Then we had the famous Reagan-Carter debate on October 28 just one week before the Nov 4 election (yes, they only had the one debate), in which Reagan completely out-classed the hapless Carter, just like Romney did in the first debate against Obama. Reagan came across as very presidential and in 90 minutes, completely devastated the mainstream media meme that Reagan was a reckless cowboy who would lead us into World War 3.
Below is an election map of the counties that Reagan won (red) compared to Carter (blue). What is rather amazing about this map is that the Deep South was still so Democratic at that time. Of course, it helped that Carter was a native of Georgia. But still, most of those blue areas in the South will be red on Tuesday night and of course, all the major cities in the Northeast, Midwest and on the West Coast will be Obama blue.
History repeats itself thanks! :)