Republicans have a major electoral map problem.

Amid all of the agita and hand-wringing about the campaign Republican presidential candidate Mitt Romney ran, the reality is that the former Massachusetts governor was operating on an in­cred­ibly narrow electoral map that made his only path to victory something close to a total sweep of the most closely contested states. That problem isn’t unique to Romney and, along with the party’s demographic disadvantages, is the biggest issue facing Republicans as the party tries to regroup for 2016, 2020 and beyond.

Let’s start with an examination of the electoral math.

In the past six presidential elections, including 2012, the Democratic nominee has averaged 327 electoral votes while the Republican nominee has averaged just 210. (A candidate needs 270, a simple majority of the total of 538 electoral votes, to be elected.)

During those two-plus decades dating back to 1992, the most — repeat most — electoral votes a Republican presidential candidate has won is 286, when George W. Bush claimed a second term in 2004. In that same time frame, Democratic nominees have received more than 300 electoral votes four times: Barack Obama in 2008 (365) and 2012 (332) and Bill Clinton in 1992 (370) and 1996 (379). The lowest total for a Democratic nominee during that period was Sen. John Kerry’s 251 electoral votes in 2004; Republicans’ floor during that same period was 159 electoral votes in 1996.

That Democratic electoral-vote dominance is the mirror image of the huge edge Republicans enjoyed in the six elections prior to 1992. From 1968 to 1988, Republican presidential nominees averaged a whopping 417 electoral votes per election while Democrats managed just 113. The most electoral votes a Democratic nominee won was 297, when Jimmy Carter claimed the presidency in 1976. Ronald Reagan, in beating Carter four years later, rolled up 489 electoral votes — and followed that up with a 525-electoral-vote victory in 1984. From 1968 to 1988, Democrats never broke 300 electoral votes, while Republicans broke that barrier five times: 1968 (301), 1972 (530), 1980 (489), 1984 (525) and 1988 (426).

The numbers paint a very clear picture: Republicans now face the same low electoral-college ceiling that Democrats confronted for much of the 1970s and 1980s — needing everything to go right to win the presidency, much less break the 300-electoral-vote barrier.

Why the switcheroo? A few reasons.

Large-population states (and, hence, major electoral-vote treasure troves) such as California, New York, Pennsylvania, Illinois and Michigan have gone from swing states to reliably Democratic enclaves. President Obama’s victories in those five states alone delivered him 140 electoral votes Tuesday, more than half the total he needed to win. Republicans have far fewer in-the-bag states; Texas and its 38 electoral votes is the only huge prize that is consistently in the Republican column. (Carter was the last Democratic presidential nominee to carry the Lone Star State.)

Meanwhile, Democrats have expanded their map in recent years thanks to the large majorities they win among black and Hispanic voters and the increasingly smaller share of the vote that whites constitute. States such as North Carolina, Virginia and Florida have all gone from generally reliable Republican states to real swing states. (Obama carried Florida and Virginia in both 2008 and 2012; he won North Carolina in 2008 and narrowly lost it in 2012.) There has been no similar Republican map expansion; Romney won no state that Bush didn’t win in 2004 and lost six — Colorado, Iowa, Florida, Nevada, New Mexico and Ohio — that Bush won eight years ago. Attempts by Romney to expand the map in Pennsylvania and Wisconsin backfired; he lost both states by larger margins than Bush did in 2004.

Not all of the news is bad for Republicans. In the last reapportionment of congressional districts, based on the 2010 Census, 10 states lost seats. Of those 10, Obama carried eight of them in 2012 — including Ohio and New York, both of which lost two seats. Of the eight states that gained congressional seats in that process, Romney won five of them, including Texas, which gained four seats.

But even in that silver lining for Republicans, you can see clouds. Arizona and Georgia, both of which Romney carried in 2012, gained seats in 2010 because of fast population growth, but Democratic dominance among Hispanic voters in each is expected to make them potential swing states in 2016 and 2020.

For Republicans, changing their coalition from one built around older, whiter voters to one with more Hispanic (and female) faces goes hand in hand with solving their electoral map problem. But make no mistake: No matter who Republicans nominate in 2016, he/she will almost certainly be faced with the same dauntingly narrow path to 270 electoral votes that Romney came up against on Election Day.