Nate Cohn asks a great question at The Upshot:

How does a Republican Party seemingly dominated by the South, energized by the Tea Party and elected by conservative voters also consistently support relatively moderate presidential nominees?

Well-stated. And his answer is one Democrats must understand before we can formulate a winning strategy:

The answer is the blue-state Republicans…It’s easy to forget about the blue-state Republicans. They’re all but extinct in Washington, since their candidates lose general elections to Democrats, and so officials elected by states and districts that supported Mr. Romney dominate the Republican Congress.
But the blue-state Republicans still possess the delegates, voters and resources to decide the nomination. In 2012, there were more Romney voters in California than in Texas, and in Chicago’s Cook County than in West Virginia. Mr. Romney won three times as many voters in overwhelmingly Democratic New York City than in Republican-leaning Alaska.
Overall, 59 percent of Romney voters in the Republican primaries lived in the states carried by President Obama. Those states hold 50 percent of the delegates to the Republican National Convention, even though they contain just 19 percent of Republican senators. Just 11 percent of House Republicans hail from districts that voted for President Obama.

Kind of paradoxical. We have been repeatedly told that “moderate” Republicans, such as they are, must run to the right to get their party’s nomination. Yet, the GOP has a bias toward the more moderate candidates on nomination day.

For all the legitimate attention that will be given to questions about whether an establishment favorite like Mr. Bush can win over deeply conservative voters, there are just as many questions about which conservative candidate can win over blue-state Republicans. Mr. McCain and Mr. Romney won every blue-state primary in 2008 and 2012, making it all but impossible for their more conservative challengers to win the nomination.

Cohn trots out charts indicating that the 18 “bluest states…have dwindled to 7 percent of the G.O.P.’s Senate delegation…But they still account for 4 in 10 voters in Republican primaries, helping swing results toward establishment candidates.” Cohn adds,

The importance of blue-state Republicans makes it far less likely that the party will nominate a conservative firebrand or a favorite of the religious right, like Ted Cruz or Mike Huckabee, than one might guess from the unwavering conservatism of the red-state electorates that hold sway over elected Republicans in Washington…If the Republican presidential nominee were decided by the red states — by the same electorates that send Republican officials to Washington and then dissuade them from even the most incremental compromises — then Mr. Romney and Mr. McCain probably wouldn’t have won the party’s nomination.
Cohn cites a somewhat similar trend with Democrats, noting that a left progressive Democratic presidential candidate “might win San Francisco, Boulder, Colo., or Vermont, but would struggle to win relatively conservative Democrats in Appalachia or the South,” which should give added comfort to Hillary Clinton. Conversely, former FL Gov Jeb Bush and WI Gov. Scott Walker will find Cohn’s analysis heartening (NJ Gov. Christie would also be included here, but for his still-festering scandals. If Scott Walker’s ethical issues explode, the smart money in Cohn’s analysis is on Jeb Bush).

An interesting insight, especially for those of us who find the party conventions more boring than not, with their ritualistic rah rah, ho-hum platform deliberations and predictable displays of unanimity at closing time. The Republican primaries in blue states and Democratic primaries in red states have a lot more to say about the direction of the country than is commonly believed.
As for the money primary, Cohn notes some geographic overlap:

The clout of blue-state Republicans is enhanced by an alliance with the party’s donor class. Republican donors, in general, are likely more concerned by electability and business issues than religiosity and the culture wars. But they also come disproportionately from the blue states, which accounted for 62 percent of all Republican primary fund-raising in 2012. A candidate like Gov. Chris Christie of New Jersey or the former New York mayor Rudolph W. Giuliani in 2008 might be too moderate to win the nomination, but would have a far easier time raising money than a highly conservative candidate like Mr. Santorum.

In the GOP, the culture warriors get all the press but the economic conservatives get the dough. No doubt the Koch brothers would likely be happy enough with Jeb Bush, but an unrepentant union-basher like Scott Walker probably gives them a political stiffie.
Cohn notes exceptions, like Bush II mining his evangelical creds to win his party’s nomination. But you can’t so easily factor out his blue state bloodlines. In any event, he’s more the exception that proves the rule. Overall, Cohn’s analysis squares well with recent history.
Bottom line, if Cohn is right, don’t pay too much attention to the clown car culture warriors of the red states. The Republican nomination is more about who is the shrewdest of their blue state slicksters.