Republican presidential candidate Sen. Ted Cruz speaks to the crowd at the GOP caucus in Wichita, Kan., on Saturday. (AP Photo/Orlin Wagner)

With Sen. Ted Cruz (R-Tex.) assured of victory in Kansas's caucuses, two themes of the Republican primary have come into sharper relief. In contests that are limited to Republican activists, Cruz benefits and Donald Trump struggles. And the endorsements of state governors do not appear to be changing the trajectory of the race anywhere.

Cruz's strength in "closed" primaries and caucuses had been intriguing conservative activists since Super Tuesday, when -- in the night's truest upset -- Cruz won Alaska's caucuses. Radio host Bryan Fischer and RedState writer Moe Lane were among the conservatives asking why Trump fared best when independents were allowed to cross over into Republican primaries.

In New Hampshire, which started Trump's roll across the map, 39 percent of undeclared voters chose him, compared to 33 percent of registered Republicans. Had South Carolina's primary been limited to Republicans, Trump would have prevailed by a 32-24 margin over Cruz; Cruz ran a poorer third among independents, who made up 22 percent of the electorate.

But Alaska's caucuses -- like Oklahoma's primary, also won by Cruz -- were open only to Republicans. To caucus in Kansas, a voter had to have registered with the Republican Party by Feb. 4. The sparse Kansas polls suggested that Trump held a narrow lead, but the actual contest gave Cruz the same sort of landslide enjoyed by former senator Rick Santorum of Pennsylvania in 2012 and former Arkansas governor Mike Huckabee in 2008.

Trump was not alone in the Kansas rubble. With nearly three-quarters of caucus sites reporting, Sen. Marco Rubio (R-Fla.) is on track for a weak third place, statewide and in every Kansas congressional district. That's striking when compared to the amount of institutional support Rubio got along the way. On Feb. 15, Kansas Gov. Sam Brownback (R) became the first sitting governor to endorse Rubio. Three days later, Sen. Pat Roberts (R-Kan.) endorsed Rubio. And after Jeb Bush quit the presidential race, retired senator Bob Dole, a native of Russell, Kan., switched his endorsement over to Rubio.

None of it mattered. Kansas has joined Oklahoma, Arkansas, South Carolina and Tennessee in the family of states where Rubio locked up a Republican governor's endorsement, then lost the contest. In that same time period, Gov. John Kasich (R-Ohio) rode the endorsement of Gov. Robert Bentley (R-Ala.) all the way to a last-place finish in Alabama's primary.

In Maine, which went unpolled all year, Trump entered the evening expecting to lose in an upset to Cruz; Gov. Paul LePage (R-Maine) was the only sitting governor to endorse Trump. But more worrying for Trump might be the rules that allowed Maine's independent voters to caucus in whichever party contest they liked.