Washington (CNN) President Donald Trump made one thing very clear over the last few months: He badly wanted Utah Republican Orrin Hatch to run for another Senate term.

At an event in Utah in December, Trump said this of Hatch

"You are a true fighter, Orrin. And I have to say, I've gotten to know him very well. I've gotten to know a lot of people very well. You meet fighters and you meet people that you thought were fighters but they're not so good at fighting. He's a fighter. We hope you will continue to serve your state and your country in the Senate for a very long time to come."

Hatch traveled to and from that Utah event with Trump on Air Force One.

At the bill signing event on Trump's tax cut legislation just days before Christmas , Trump called the Utah Republican "the great Chairman Orrin Hatch," adding: "Great job, Orrin. Wow. Orrin is a special person."

As far back as March 2017, Trump was actively lobbying Hatch to stay. "His pitch is he needs me," Hatch told CNN's Manu Raju of Trump . "Things are going to be just fine."

That long and aggressive full court press from the President of the United States makes Hatch's decision, announced Tuesday afternoon, that he wouldn't run for an eighth term all the more intriguing.

In the immediate aftermath of the news of Hatch's retirement, White House press secretary Sarah Sanders allowed that Trump was "very sad to see Senator Hatch leave," adding: "The President has the greatest and deepest amount of respect for Senator Hatch."

It's certainly too much to lay Hatch's retirement at the feet of Trump. Hatch, had he run for an eighth term, would have been 89 at the end of that term. He had made very clear -- even before Trump was elected President -- that he was unsure about whether he would run again in 2018.

But it is still worth noting that the Republican President of the United States spent much of the last year urging a prominent Republican senator to run for re-election -- and it didn't work.

That's especially important because it's long been suspected -- and reporting bears this out -- that one of the reasons Trump was so gung-ho for Hatch to run again was that he did not want an open seat situation where two-time presidential candidate Mitt Romney could run.

Should he run -- and most Utah insiders expect him to -- Romney would start the race as the front-runner. While that doesn't mean he is a lock for the Senate -- Utah's Republican nominating process could open the door to a challenge from Romney's ideological right -- it does suggest that the odds favor Romney at the moment.

Here's a very simple way to understand the difference for Trump between Senator Orrin Hatch and Senator Mitt Romney.

"This President hasn't even been in office even a year, and look at all the things that he's been able to get done," Hatch said of Trump in late December. "By sheer will in many ways."

"Donald Trump is a phony, a fraud," Romney said of Trump in March 2016 . "His promises are as worthless as a degree from Trump University. He's playing members of the American public for suckers: He gets a free ride to the White House, and all we get is a lousy hat."

Big. Difference.

There was a time when Romeny and Trump appeared to have mended fences. Trump very publicly considered Romney to be his secretary of state. The two had dinner, which resulted in this very awkward photo:

President-elect Donald Trump and Mitt Romney dine at Jean Georges restaurant, November 29, 2016 in New York City.

But in hindsight that feels like an alpha dog move by Trump. There was no offer extended to Romney and he has not shied away from criticizing Trump since then. That same day Trump was publicly calling on Hatch to run for re-election, Romney was subtweeting Trump, arguing that Trump's preferred candidate in Alabama's special US Senate election, accused child molester Roy Moore, would stain the party.

"No vote, no majority is worth losing our honor, our integrity," Romney tweeted.