For so long, he was the putative front-runner, the nominal front-runner, the weak front-runner. Then he became the all-but-certain nominee. And by Tuesday night, he’ll be able to ditch those modifiers.

Willard Mitt Romney is about to do what his father didn’t and no one in his church ever has. With Tuesday’s Texas primary, he is poised to secure the 1,144 delegates required to clinch the Republican presidential nomination at the party’s August convention.

It seems like forever ago that Rick Santorum and Newt Ging­rich were waving Etch a Sketches at their rallies in a last-ditch bid to stop Romney’s march to the nomination. The long slog of primaries effectively ended on April 3 with Romney’s victory in Wisconsin. Three weeks after that, the former Massachusetts governor returned to New Hampshire, where he launched his campaign on a windswept farm one year ago this week, to claim the mantle of nominee.

But it should become official on Tuesday, when Texas voters are expected to push Romney over the finish line in the delegate race. And with that, the Republican Party will have selected an unlikely standard-bearer for 2012: a New Englander in a party rooted in the South; a man of moderate temperament in a party fueled by hot rhetoric; a Mormon in a party guided by evangelical Christians; a flip-flopper in a party that demands ideological purity.

So it was that nobody anointed Romney. There was the humbling tumult of South Carolina, where a resurgent Gingrich threw him off balance; where he stammered on the debate stage trying to explain his taxes; where one rally crowd was so meager, about 80 people in a cavernous convention hall, that he reached for excuses — “Gosh, this is a workday, right?”

On the day South Carolinians voted, Romney, in his mind already defeated, found order in a simple chore: He fed quarters into a washer and dryer in the Columbia Marriott’s guest laundry room.

He came back 10 days later in Florida, going on the warpath to eviscerate Gingrich, only to step on his own momentum the morning after his victory by saying, “I’m not concerned about the very poor.”

A formidable adversary

After a year of criticism that he didn’t have the strength or shrewdness to take on President Obama, Romney has emerged from the bruising primary as a formidable adversary. With the race firmly in general-election mode, he is a more disciplined campaigner than he was a few months ago and has pulled even with Obama in many national and swing-state polls.

However reluctantly they may have settled on Romney, most Republicans are now rallying behind him. On Monday, about 5,000 people — one of the largest crowds of his campaign — turned out to see him pay tribute to veterans in San Diego.

Romney started sensing that enthusiasm on a cold morning three days after Christmas. He awoke in Muscatine, Iowa, and headed to a coffee shop for a quick campaign stop. It was before dawn, but his supporters had filled the cafe, snaked down a hallway and lined up in the street. Romney’s top strategist, Stuart Stevens, said he overheard a woman telling her child, “We’re here to see the next president.”

For a campaign used to having to place robo-calls and blast out e-mails to generate a crowd, this was a shock. A few hours later in Clinton, Iowa, another shock: So many people turned out to see Romney give his stump speech at Homer’s Deli & Sweetheart Bakery that he gave a second speech at Rastrelli’s, an Italian restaurant across the street.

“What a crowd! What a welcome!” Romney gushed, a little bewildered. “This response in Clinton comes as a bit of a surprise, I have to tell you.”

Now, five months later, Romney is set to make history as the first Mormon to become a major party’s presidential nominee. At age 65, he has finally achieved what his hero — his father, George — did not. George Romney, who had no college degree and as a young man sold aluminum paint cans from the back of a truck, became head of an automobile company and governor of Michigan. When he ran for president in 1968, how­ever, the GOP nomination eluded him.

It didn’t elude his youngest son. But Mitt Romney’s team is not interested in reminiscing. Asked to recall the highs and lows of the campaign, one top aide said that she is “not too interested in looking back” but would talk about “something looking ahead.” Other senior aides didn’t even respond.

A campaign diary

Romney remembers these moments, however. He has been keeping a campaign diary on his iPad, as he recently told the Wall Street Journal’s Peggy Noonan, to capture “the feelings — the ups and downs, the people I meet and the sense I have about what’s going to happen. It’s kind of fun to go back and read, as Ann and I do from time to time.”

One of those diary entries might be from the day last September when Romney piloted his ferry across a foggy Lake Huron to Mackinac Island, Mich., the summer playground of his youth where he fell in love with Ann, his high school sweetheart. Behind the wheel of the boat, he recalled taking her there for her 16th birthday. They rode around on bicycles and horses, went boating and ate lots of fudge.

Romney journeyed back to this island of horse-drawn carriages and colorful cottages last fall to address a Republican dinner at the storied Grand Hotel. When Ann joined her husband onstage in the resplendent ballroom, people clinked their glasses and the couple kissed.

Mitt Romney then delivered what still stands as one of the better speeches of his campaign. Speaking with no notes, he cast his candidacy in epic terms.

“I believe in America,” he said, repeating his campaign slogan. “I believe in freedom. I believe in opportunity. I believe that when the Founders crafted this country, they gave us not only political freedom, the right to choose who would represent us in Washington, they gave us economic freedom, the freedom to choose our course in life.

“And by virtue of those two freedoms,” he continued, “people from all over the world — seeking freedom, seeking opportunity — every pioneer wanted to come to America. And come they did, by the millions.”

Romney quoted by heart verses from “The Coming American” by Sam Walter Foss, a poem he began reciting on the campaign trail last summer in New Hampshire:

“Bring me men to match my mountains;

“Bring me men to match my plains.

“Men with empires in their purpose,

“And new eras in their brains.”

Then the Romneys retired to their suite. Unwinding with a couple of close aides, the man who would be president rubbed his wife’s aching feet and wondered if he might someday match the mountains.