What started in the chilly wind of a surprisingly snowless Iowa has ended in the early summer heat of Texas.

On Tuesday, Mitt Romney won the Texas primary and, with it, enough delegates to carry him over the threshold to finally secure the Republican nomination for US president.

It has been a long and difficult campaign for the former Massachusetts governor. He built his campaign on the inevitability of victory, but he was certainly tested throughout.

Romney is the first Mormon to win the nomination - a branch of the Christian religion which is often regarded as a cult or a bizarre sect by others. And he goes one better than his father, George, who tried and failed to win the Republican nomination in 1968.

Willard Mitt Romney, to give his full name, won only one of the first three contests. Defeat in Iowa was narrow, but it came to a man - Rick Santorum - who a week before the poll had seemed to many to be a rank outsider.

Dangerous point

Romney won comprehensively in New Hampshire, but that was expected.

He lost in South Carolina, and that perhaps was the most dangerous point in his campaign.

It is often said that the road to the White House goes through South Carolina, and that no Republican has won the nomination without winning there.

He lost, and he lost heavily to Newt Gingrich.

However, to his credit, Romney gathered himself up and performed well in two crucial debates, organised well on the ground, and landed the victory in Florida. He also spent a significant amount of money on negative TV ads.

As a winner-takes-all state, he took all the delegates available. As a key state in the general election, he proved he could do well there. It was a significant moment.

Newt Gingrich made noises about staying in the race, about winning all the other contests, about a southern strategy and, in the end, had to leave the race with cash, influence and support disappearing.

For his part, Rick Santorum won some important contests and pushed Romney harder to the right than perhaps he would have liked. But he too ran out of money and buckled under the better organisation of his main rival.

Romney vs Obama

Romney was in Las Vegas when he heard about his win. He was at a fund-raiser. It's a necessary step, even for the multimillionaire, as he is up against the best funded candidate in US political history.

And he knows, in the world's gambling capital, that the Republican party is taking a massive risk with him.

The conservatives are not sure that he is "one of them". They look to his only previous electoral success - winning the governorship for the Republicans in the overwhelmingly Democrat state of Massachusetts.

There he presented himself as a moderate, who took liberal positions on social issues such as abortion and gay rights, although he has always opposed gay marriage.

To win the nomination now, his position on these and other issues has moved more to the right.

He pinpoints a couple of occasions which led to an epiphany - certainly on abortion - and brought him closer into line with the thinking of the core of the Republican party.

'Liberal Mitt'

That it happened as he was setting up his first run for the presidential nomination is perhaps just coincidence.

But that leaves the question: Was "Liberal Mitt" a social conservative all along who just told the people of Massachusetts what they wanted to hear? Or is he really a closet liberal who knew he needed to change his position to swing the Republicans who are most likely to vote in the primary behind him?

Now that he has the nomination, he will avoid talking about social issues as much as possible because of the awkward questions it throws up and the need to appeal to independent and centrist voters who will decide this election.

It also plays to his strength, and to Obama's biggest weakness, if he spends more time addressing the state of the economy.

But in the next few months, the former governor must now present himself to the wider electorate who have undoubtedly heard of him but won't know much about him.

And he must reveal the real Romney.

Follow Alan Fisher on Twitter: @alanfisher