Mitt Romney earned the leadership nod the hard way – through a long, gruelling campaign and a display of organization and money power.
While he did not move hearts, he did appeal to the intellectual sense of Republican voters – that an 'electable' candidate is needed to go up against President Barack Obama in November.
So why can't the former Massachusetts governor earn an enthusiastic, I-love-this-guy endorsement from one of his former opponents?
Because the love just isn't there. And nothing quite captured it like Rick Santorum's late Monday night e-mail to supporters, which set a new low for lacklustre endorsements.
The statement called for an "all hands on deck" approach to defeating Mr. Obama.
While Mr. Santorum said he intended "to keep lines of communication open" with Mr. Romney and his campaign – something once-warring campaigns should probably do as they turn their attention to a general election campaign – there was no indication of a joint Romney-Santorum campaign appearance any time soon.
If the aim was to give Mr. Romney the biggest possible bump from a Santorum endorsement, the former Pennsylvania senator achieved the opposite: an endorsement that instead fell flat and highlighted the ongoing divisions in the party.
Mr. Santorum talked about how it was "impossible" to endorse Mr. Romney until he had the opportunity to assess Mr. Romney's commitment to conservative issues and ensuring that the voices of "social conservatives, tea-party supporters, lower- and middle-income working families" were heard.
Mr. Santorum got his opportunity to sit down with Mr. Romney at an hour-long meeting in Pittsburgh last Friday.
The Santorum letter posted late Monday night is largely an attempt to protect the Santorum brand, which, as the former candidate was keen to point out, earned the support of over 3-million voters and 11 state contests.
Mr. Santorum wants to show that even in endorsing Mitt Romney, he continues to kick the candidate's tires on key social and economic issues – a tactic that will no doubt help Mr. Santorum in 2016, if Mr. Romney loses this November.
To be clear, Mr. Santorum did at least use the word 'endorsement.'
"Governor Romney will be [the Republican presidential]nominee and he has my endorsement and support to win this, the most critical election of our lifetime," read the statement, which was also posted on his web site.
Compare that to Newt Gingrich's 'kind-of' endorsement last week when he suspended his campaign and 'embraced' Mr. Romney.
"As to the presidency, I'm asked sometimes, 'Is Mitt Romney conservative enough?' And my answer is simple: 'Compared to Barack Obama?' This is not a choice between Mitt Romney and Ronald Reagan, this is a choice between Mitt Romney and the most radical leftist president in American history," Mr. Gingrich told reporters in Arlington, Virginia.
And that has been the trend – endorsements characterized by faint praise, lack of enthusiasm and being very late.
Minnesota Congresswoman Michele Bachmann endorsed Mr. Romney four months after dropping out of the race.
In late April, Texas Governor Rick Perry, who once described Mr. Romney as a "vulture capitalist" instead of a venture capitalist, issued a statement saying "...Mitt's vision and record of private-sector success will put America back on the path of job creation, economic opportunity and limited government."
Former Utah governor and U.S. ambassador to China Jon Huntsman, who once said Mr. Romney lacked a "core" because he had changed his policy positions so many times, offered a tepid endorsement during a Florida news conference in January after dropping out of the race.
"I believe it is now time for our party to unite around the candidate best equipped to defeat Barack Obama. Despite our differences and the space between us on some of the issues, I believe that candidate is governor Mitt Romney," Mr. Huntsman told a news conference.
Mr. Santorum delivered some of the sharpest criticisms of the Romney candidacy during the leadership campaign.
He questioned whether Mr. Romney and his track record in health-care reform while governor of Massachusetts – a model that has been described as a template for Obamacare – was the best candidate to make the case for repealing Mr. Obama's signature legislation.
Mr. Santorum's statement on Monday night indicated that he had no doubt that "if elected [Mr. Romney]will work with a Republican Congress to repeal it and replace it with a bottom-up, patient, not government-driven system."
That is a sharp turn from his statement about Mr. Romney in the heat of the leadership contest: "Pick any other Republican in the country. He is the worst Republican in the country to put up against Barack Obama."