Will Republican voters finally listen to the party's elders and stop supporting Donald Trump?
Saturday's contests in Kansas, Kentucky, Louisiana and Maine are the first races since Mitt Romney delivered his forceful denunciation of Trump and urged the party faithful to block his path to the GOP nomination. Romney was not alone this week, as John McCain also condemned the real estate mogul, and dozens of Republican policy experts, including former Homeland Security Secretary Michael Chertoff, released a public letter saying they could not vote for Trump.
Here's a closer look at Saturday's contests:
Trump's Potential wins: Maine (23 delegates) and Louisiana (46 delegates)
So far in the primary process, Trump has performed very well in two kinds of areas: states in the northeast (Massachusetts, New Hampshire, Vermont) with relatively small numbers of evangelical Christians and states in the south (Alabama, Mississippi, South Carolina) with large black populations and disproportionately high numbers of whites who don't have college degrees.
Louisiana would seem to fit the pattern of the kind of Southern state where Trump will perform well. Only about 22 percent of its residents over age 25 have college degrees, compared to about 29 percent in the United States overall. Its black population is 32 percent, compared to 13 percent in the U.S. overall. (African-Americans are not voting for Trump, but he has over-performed among the white Republicans who live in areas with lots of blacks.)
In 2012, Rick Santorum defeated Mitt Romney in Louisiana by 22 points, as very conservative and evangelical voters overwhelmingly backed him. Santorum's success suggests a path in Louisiana for Texas Sen. Ted Cruz, who is winning evangelicals and very conservative voters in many states.
But Trump dominated Cruz in the south on Super Tuesday outside of Texas. He seems likely to win in Louisiana on the strength of white voters without college degrees.
Maine, unlike the northeastern states that voted earlier, is holding a caucus, and there is some evidence from earlier states that Trump does better in primaries than caucuses, which tend to draw smaller electorates. If a candidate with a strong organization and appeal to non-evangelical Republicans (say Rand Paul) remained in the race, that person would be a very formidable challenge to Trump in Maine.
In this field, Trump's competition is two religious candidates (Florida Sen. Marco Rubio and Cruz) and one who does not seem to have a great "ground game" (Ohio Gov. John Kasich.)
And if there is one sitting Republican office-holder who is similar to the bombastic Trump, it is Maine Gov. Paul LePage, who has now endorsed the mogul.
A Potential Trump Loss: Kansas (40 delegates)
Trump has lost in five states: Alaska, Iowa, Minnesota, Oklahoma and Texas.
Kansas has many similarities to the place where Trump has struggled. Like Minnesota, Kansas has lots of college graduates (31 percent of the population), so fewer of the white-working class voters who strongly favor Trump. It is an overwhelming-white state but outside of the northeast, like Iowa and Minnesota. And Kansas is holding a caucus, not a primary, like Alaska, Iowa and Minnesota.
Kansas' Republican Party activists, the type of people likely to turn out in a caucus, are traditionally very socially-conservative, church-going and opposed to abortion rights, again not the core traits of Trump voters.
These factors favor either Cruz or Rubio winning there, as they did in Alaska (Cruz), Iowa (Cruz) and Minnesota (Rubio.)
A Wild Card: Kentucky (46 delegates)
Kentucky is holding a caucus and has a relatively small black population. So even while the state is in the south, it's not as favorable ground for Trump as Louisiana.
On other hand, Kentucky is another state with a large population of white voters without college degrees, Trump's base.
If Kentucky were holding a primary, Trump would be a heavy favorite. But in a low-turnout caucus, Cruz in particular could win by appealing to the college-educated, conservative Republicans around the cities of Louisville (Jefferson County) Lexington (Fayette County) and Cincinnati (Boone County, Kentucky).
On the Democratic Side, Watch for Margins
If the early stages of the campaign are any guide, there will be little drama to the results in the Democratic races. Kansas, Maine (which votes on Sunday) and Nebraska are holding caucuses in overwhelmingly-white states. Those environments are very favorable to Sanders, who has done well in caucuses (Colorado, Minnesota) and states with small minority populations (Minnesota, Vermont.)
Louisiana's electorate is likely to be about half African-American, putting Clinton at a huge advantage there, since she has won more than 80 percent of the black vote in the early rounds of primaries.
So far, Clinton is winning the race for delegates in part because she is doing better in very-white states than Sanders does in very-black ones. In short, Clinton is being blown out in states where the demographics don't favor her, but not as badly as Sanders is.
For example, on Tuesday, Clinton won six states with more than 60 percent of the vote, compared to Sanders doing that well in just two states.
And Clinton has even won a couple of states (Iowa, Massachusetts) where the demographics (low black populations) favored Sanders.
So on Saturday, Sanders will be looking to exceed 60 percent of the vote in Kansas, Maine and Nebraska, and alternatively, not lose by a similar margin in Louisiana.