But if there was one campaign subplot that best illustrated Romney's tortured relationship with the base, it was the curious case of Donald Trump.

Some Republicans assign blame to a campaign high command devoid of movement conservatives, which was fundamentally disconnected with the party's base. Others attribute the overlong courting of conservatives to insecurity on the candidate's part.

Before that, he was consumed by a desperate bid to make Republicans like him; chasing Joe Biden's gaffes, courting conservative blogs, and doling out hot dogs at NASCAR races. It was a preoccupation that bordered on obsession, and it ate up time before Romney could finally find his footing as a candidate, delivering a sharp debate performance, pivoting to the political center, and campaigning on the economy.

And he did get to run that campaign — but not until the last four weeks of the election.

"I wasn't in the room when they decided that Mitt was going to have to be more conservative than [Rudy] Giuliani and John McCain in order to win the primary, but I would have advised against it," said one longtime friend and adviser to Romney in the spring 2011. "Those social issues weren't his strong suit, and I think some people thought he was a phony... But now Republicans, and people in general, want someone who understands the economy, and that's the campaign he will get to run."

At the outset of 2012, many of Mitt Romney's confidantes, friends, and advisers were hopeful that the political climate would let him play to his strengths as a successful businessman and be himself. He had wasted a grueling 2008 presidential bid role-playing as a right-wing culture warrior, a part that never quite suited him, in the eyes of many of his allies.

But perhaps the campaign's most fatal mistake was its tortured, 16-month quest to win the affection of rank-and-file conservatives via their most boisterous mouthpiece — at the expense of almost everything else.

BOSTON — The Romney campaign obituaries that will litter the Internet over the coming days and weeks are bound to offer varied causes of death: tactical mistakes, candidate gaffes, shifting demographics, or some poisonous mix of bad luck and blunders.

In spring 2011, Trump had floated the idea of his own presidential run, with his main platform plank having to do with exposing President Obama's fraudulent citizenship. His bombastic birtherism — and the relentless media attention it attracted — was enough to propel him to the top of some early Republican primary polls. He ultimately decided not to run, but reserved the right to endorse.

Trump's appeal to the Republican base was undeniable, and, to many on Romney's staff, utterly perplexing. Among the savvy sophisticates who populated the campaign headquarters in Boston, Trump was viewed as a joke and a blowhard — an outrageous figure whose fixation on Obama's birth certificate was, at once, bizarre and off-putting, according to campaign sources.

But he was also popular among the very voters Romney was most concerned about winning over. And the candidate's aides believed — perhaps naively — that if they could win his endorsement, they might be able to win the hearts of his many conservative fans.

"He played very well with blue-collar-type Republicans, and the campaign saw that," said one source in Trump's camp. "If you have no education, and you work with your hands, you like him. It's like, 'Wow, if I was rich, that's how I would live!' The girls, the cars, the fancy suits. His ostentatiousness is appealing to them."

When the campaign decided to go for it, they went all out. Staffers and surrogates lobbied their contacts in Trump's office, and senior campaign strategist Stuart Stevens called a person close to the Celebrity Apprentice star and asked what they could do to win him over.

The friend's advice: "Flattery goes a long way with Mr. Trump."

And so, in September 2011, the candidate himself paid a visit to Trump Towers in New York City. Other GOP contenders had already made the journey to kiss The Donald's ring — including Herman Cain, Michele Bachmann, and Rick Perry — but Romney was considered the most serious candidate at that point. Rather than hold a big press conference outside the building like others did, Romney slipped in and out of a back door, dodging the photographers lurking nearby.

No one knows what was said behind those closed doors — only Romney and Trump were present — but whatever it was, the candidate had "charmed" him, according to a source who spoke to Trump afterward. The source added that Trump had seriously considered backing Perry, but Romney's meeting put him over the edge.

"I think it's a rich-guy thing," Trump's friend told BuzzFeed.

By the time the deal was finally sealed, several of the campaign staffers in Boston had grown so sick of Trump's demands that they refused to deal with him anymore.

The task of keeping him happy, then, fell mainly to campaign press secretary Andrea Saul, a natural schmoozer with a disarming Georgia accent and an inordinate tolerance for BS. Trump's entourage called campaign headquarters constantly, eagerly passing along strategy ideas from their boss, and the calls were always patched through to Saul's office. Her desk became littered with Trump aides' business cards, and post-it notes reminding her to call them back. (Saul did not respond to BuzzFeed's request for comment.)

The day of Trump's official endorsement came February 2, just after Romney beat back another conservative primary rival — this time, Newt Gingrich — by carpet-bombing Florida with attack ads. The campaign was riding high, hoping against hope that the Trump endorsement would help them rally Republicans behind his candidacy so he could begin focusing on the general election.

As part of their negotiations, the Romney campaign had agreed to announce the endorsement with a press conference held at Trump's Las Vegas hotel. The Donald was having the time of his life, roaming around the lobby and holding not one, but three separate press gaggles. He bragged about the lengths to which the campaign had gone to court him, and he made a point of plugging his hotel.

"You can see why it's number one in Nevada!" he declared.

Campaign aides could be seen rolling their eyes, but they were under strict orders to keep him happy, a campaign official said. At one point, Trump looked out over the press section — comprised mostly of a few local reporters, and the campaign's typical traveling press — and squinted at Saul as he fished for compliments.

"Andrea, have you ever had this many reporters at an endorsement?" he asked.

"Never," she responded, dutifully.

He then turned to a campaign advance staffer, and asked the same question. He hesitated at first, but then offered, "It's more than normal." Trump nodded, satisfied.

But for all the campaign's herculean efforts to appease Trump and his outsize ego in pursuit of conservative approval, Romney hardly looked comfortable on stage as his newest supporter delivered a grandiose — and vaguely self-serving — address. When it was time for the photo op, Romney angled, ever so slightly, away from the camera. And when he had to come to the microphone, he looked as though he couldn't believe what he was doing.

"There are some things you just can't imagine happening," Romney said. "This is one of them."

Even one of Trump's aides conceded, of the afternoon, "[Romney] looked about as sheepish as you can get. He looked like a guy going to a dentist's office."

Of course, the Trump stunt did not end up sending Tea Partiers marching en masse to the primary polls to cast their vote for Mitt Romney. The robo-calls the campaign had Trump record did little to prevent the rise of more conservative challengers, and Romney would spend the next 10 weeks waging hand-to-hand combat with Rick Santorum — draining his war chest in the process, and distracting himself from his eventual general-election opponent.

When Romney finally emerged as the nominee, his association with Trump became, increasingly, a political headache. The reality-TV star wouldn't drop his obsession with the president's past and personal life, and as recently as last month, he publicly offered to donate $5 million to the charity of Obama's choice if the president agreed to release his college transcripts. Then, when Hurricane Sandy decimated parts of the East Coast, killing scores of people, Trump tweeted that he would extend the offer an extra couple of days "because of the hurricane."

While Republican primary voters might have found such antics viscerally satisfying — or at least easy to ignore — they were far less palatable to swing voters and moderate independents. Realizing this, the Obama administration did everything they could to tie Romney to Trump.

"Donald Trump is Mitt Romney’s biggest supporter, so he owns everything he says," senior White House adviser David Plouffe said last month.

Trump, meanwhile, refused to let off, believing, as one of his friends said, "in his heart of hearts that he's helping... Everywhere he goes, people are telling him, 'You’re right about this birth certificate issue!' He obviously believes it's legit."

He also required constant maintenance by the campaign to keep him from going completely off the rails. When he demanded a speaking slot at the Republican National Convention, the campaign talked him down to a safer, five-minute video — produced by senior campaign media strategist Russ Schriefer. According to one source familiar with the video, it was built around Trump delivering his signature line — "You're fired!" — to President Obama. The video never saw the light of day, though: The campaign scrapped it when Hurricane Isaac forced the cancellation of the program's first day. And Trump's vocal reactions to every scheduling change, of course, produced a slew of headlines. (Schriefer did not respond to queries.)

But even after all the hassle, Romney was extremely reluctant to publicly cut ties with Trump. Some in the campaign worried it would draw unnecessary attention to an episode they'd rather be forgotten in the general election, while others thought Trump might turn his powers of provocation on Romney if they snubbed him — drawing the ire of that elusive "base."

So Trump barreled along toward Election Day, ostensibly supporting Romney but ultimately unwilling to do what was necessary to get him elected (in this case, laying low and keeping his mouth shut). He used Romney's candidacy as a vehicle to rail against the president he hated, and when he was feeling generous, he occasionally paid lip service to the Republican nominee. Trump even got an invite to Romney's election night victory party at the Boston Convention Center.

But, like so much of the Republican base, he was never truly converted; and the sacrifices Romney made early on to win his support were never repaid with loyalty or enthusiastic support. As returns began to trickle in Tuesday night, it quickly became clear that the much-anticipated wave of Republican turnout had fallen short in many key battlegrounds. And once it became clear the night wasn't going to work out, Trump skipped town early. According to airport records, Trump's private helicopter departed Logan Airport in Boston at 11:19 p.m. headed for New Jersey — a full hour and a half before Romney delivered his concession speech.

On his way out of town, Trump filled his Twitter feed with outraged hysteria at the election's outcome, peppering his Tweets with words like "revolution" and "sham" and "disgusting injustice."

"We can't let this happen. We should march on Washington and stop this travesty. Our nation is totally divided!" he tweeted.

One name that didn't make it into this election-night Twitter meltdown: Romney.

Michael Cohen, a spokesman for Trump, said there was no strain in the relationship between him and the Romney campaign and that he was seriously committed to getting the Republican elected.

"I doubt the veracity of any statement that questions the strong relationship between Governor Romney and Donald Trump," Cohen said. "Trump was one of Mitt’s strongest and most popular surrogates. Mr. Trump and Romney’s senior staff communicated on a continuous basis and no such complaints alleged were ever voiced. I suspect the two will continue to maintain a relationship for years to come."

But another person close to Trump said the multimillionaire's view of Romney was and is relatively similar to how much of the Republican base views him.

"Trump was obviously always genuinely anti-Obama, but he bought into the idea that as a moderate, Romney had the best chance of beating Obama," the source said. "Given the choices he had, he thought Romney."

Would they stay in touch now that the election's over?

"Trump doesn’t like to be associated with failure," the source responded. "Trump's a winner. My guess is today he’s pretty disappointed."