The Republican establishment and their dark money overlords have decided to make Wisconsin the place they draw a line in the sand against the Donald Trump juggernaut. They are throwing everything they have at Trump here - from ambush radio interviews to every Republican leader in the state attacking Trump and praising Cruz.

It's not that Cruz has a realistic chance of becoming the nominee. The establishment just wants to stop Trump to make it easier for them to manipulate the rules of the convention so that a candidate of their choice is named.

This culminated on Tuesday when Scott Walker endorsed Cruz even though he already said that he didn't think Cruz or anyone else still in the race would be the nominee. Maybe that's why Walker's endorsement sounded a little less than convincing:

Wisconsin Gov. Scott Walker endorsed Texas Sen. Ted Cruz in the Republican presidential primary on Tuesday, telling conservative radio host Charlie Sykes he's "all in" for the "common-sense conservative who ... sticks to his guns."

Walker made it clear his support for Cruz isn't the result of an "anyone but Trump" mentality shared by many Republicans; rather, he's excited about the candidate.

"To me, I'm all in," Walker said. "This is not a default."

Um, yeah. If you have to try to convince people that Cruz is not your default choice and that you were just following orders in endorsing him, well, it's not very convincing after all.

Also, when Walker dropped out of the race in record time, he tried to get the other candidates to do the same so that they could focus on beating Trump.

Walker also promised to go around campaigning for Cruz although it's not clear what a governor with a 39% approval rating is going to do to help and not hurt the campaign.

Meanwhile, Trump had been predicting that Walker wouldn't endorse him. And when Walker came out with his endorsement of Cruz, Trump slammed him but good:

Trump predicted -- correctly, it turned out -- that Walker would endorse Texas Sen. Ted Cruz in Wisconsin's April 5 presidential primary. The real estate mogul suggested Walker may have been smarting from his short-lived presidential bid. Trump took credit for knocking the Wisconsin governor out of the race.

"We sent him packing like a little boy," Trump said during the 20-minute interview. "I'm the one that revealed his weaknesses."

Walker, Trump said, left the GOP primary field "in disgrace." Trump added, "I'm surprised he's got any juice left in Wisconsin."

Trump then pointed to Walker's recall election in 2012, saying there appears to be a lot of hostility in the Badger State.

"Wisconsin has a lot of problems. Plus, there's tremendous hatred. You look at the vitriol," he said. "I wouldn't exactly say, fellas, that things are running smoothly."

While Walker was still in the running for the GOP nomination, Trump said he simply pointed out that Wisconsin was facing a $2.2 billion budget deficit, something he said the second-term Republican governor never explained.

"The schools were going begging and everything was going begging because he didn’t want to raise taxes because he was going to run for president,” Trump said of Walker. “So instead of raising taxes, he cut back on schools, cut back on highways, cut back on a lot of things.”

In the end, Trump said: "I hit him very hard. . . . Literally, in one week, he was out of the race."

Meanwhile, Ohio Governor John Kasich (remember him?) was trying to keep even a shred of relevance:

Republican presidential candidate John Kasich said he wasn't surprised that Wisconsin Gov. Scott Walker did not endorse him on Tuesday and went instead with Texas Sen. Ted Cruz.

"I kind of thought this would happen," Kasich said.

The Ohio governor intimated in stops in Milwaukee and Waukesha that Walker's decision to back Cruz was little more than a speed bump — if that — in his run for the GOP nomination.

Kasich reiterated his belief that Trump won't get the necessary delegate count to make his nomination a certainty, and at the convention in Cleveland, Republicans will eventually turn to him — someone with leadership and experience.

"I have basically labored in secrecy for a very long time — and now, all of a sudden, I kind have some of the sun shining on me," Kasich said in Waukesha.

The strategies of the three candidates are also interesting.

Cruz is rarely stepping out of his comfort zone of the three ultrared counties around Milwaukee - Washington, Ozaukee and Waukesha - where the establishment is strongest. Meanwhile, Trump is hitting a lot of the outstate places where he has the strongest support. Kasich is going anywhere and everywhere, begging to get what votes he can. Kasich said that he wants to be a spoiler for Trump, but odds are he's going to hurt Cruz worse than Trump.

On the other side, both Hillary Clinton and Bernie Sanders are drawing good crowds and getting the crowds very enthused.

And of course, with the circus going into full speed, the rest of us are just sitting back and eating our popcorn.