Sore loser Donald Trump plays a misguided game trying to delegitimize Republican delegate selection rules. During a Fox interview Monday, Trump said the selection process is “rigged, it’s crooked.” At his rally in Rochester, New York, Trump called the process “corrupt” and complained of “crooked shenanigans” being used to win delegates.

As Marc Thiessen explains, contrary to the Donald’s bellyaching, Ted Cruz is doing exactly what Ronald Reagan did in 1976, when he mounted an insurgent campaign for the GOP nomination against President Ford. Cruz, like Reagan did, is running a very well-organized ground game to win every available delegate at state and local conventions across the country. Like Trump, the Ford team complained about Reagan’s tactics:

Ford’s chief delegate hunter, James Baker, complained to Time magazine that Ford’s people were being “out hustled” by Reagan, declaring “These Reagan people don’t care; they’re absolutely ruthless. They want all of it.” Reagan traveled across the county addressing state and local conventions, and called uncommitted delegates inviting them to private dinners (adding “By the way, do you mind if I bring along John Wayne and Jimmy Stewart?”).

Unlike Trump, Ford responded in kind: The campaign invited unbound delegates to the Oval Office and sent operatives to state conventions to flip Reagan delegates to his side.

Cruz, also like Reagan did, is working to elect delegates who, while bound to support Trump on a first ballot, will support Cruz on subsequent ballots:

In Virginia’s 9th Congressional District, for example, two of the three delegates elected told The Post that “they would vote for Cruz if voting on a GOP nominee goes into multiple rounds.” In Georgia’s Coweta County — which Trump won by 12 percentage points — Cruz supporters won an estimated 90 percent of the county’s delegates to the state and district conventions that will choose Georgia’s delegates at the Republican National Convention. In Michigan, Cruz’s campaign believes it has elected its supporters to at least five of the 25 delegate slots pledged to Trump. It has been a similar story in South Carolina, Indiana, Tennessee, South Dakota and other states.

There is nothing wrong with this. All Cruz is doing is using the various state’s delegate selection rules to fight for every available delegate according to the rules, just as Reagan did. Trump has no one to blame, but himself for mounting what looks more and more like an incompetent campaign:

Back in February, after losing Iowa to Cruz, Trump admitted he “never realized” the importance of building a field organization. But instead of going out and building that field organization, he has done the opposite. Politico reports that “Since March, [Trump] has been laying off field staff en masse around the country.” Trump brags about how rich he is, but he has run his campaign on the cheap, relying on provocative tweets and his massive advantage in free media to win primaries. He’s now learning that Twitter and free media can’t win delegates.

What is especially disheartening about Trump’s new convention manager, Paul Manafort, accusing the Cruz campaign of using Gestapo tactics, is that in 1976, Manafort was the delegate-hunt coordinator in eight states for the President Ford Committee. He knows better. Both Trump and his new delegate charmer should stop complaining about the rules and try to try to play by them like the Cruz campaign.