Republican presidential frontrunner Mitt Romney tightened his hold on the party nomination Wednesday when he secured one of the most sought-after endorsements, former Florida governor Jeb Bush.
It comes on top of a commanding victory over Rick Santorum in the Illinois primary on Tuesday night, a potential turning-point in a race that has acquired an air of inevitability.
Bush, in his statement throwing his support behind Romney, applied pressure to Santorum to quit the race and for the Republicans finally to unite behind one candidate: Romney.
Bush said: "Primary elections have been held in 34 states, and now is the time for Republicans to unite behind governor Romney and take our message of fiscal conservatism and job creation to all voters this fall."
Romney described the endorsement as a key point in the campaign. But in a mis-step that took some of the shine off the Illinois win and the backing of Bush, one of his Romney's advisers, Eric Fehrnstrom, made light of the candidate's tack to the right during the nomination process, saying the positions could be reset "like an Etch-a-sketch".
It was a rare gaffe: usually it falls to Fehrnstrom and his team to clean up after the badly chosen words of their boss.
His rivals tried to capitalise on the mistake, but the fact remains that Romney is now in a strong position. Although he is still well short of the 1,144 delegates to the party convention in August required to secure the nomination, the remaining races between now and June are favourable to Romney. Santorum needed an upset in Illinois and failed to achieve it.
Most endorsements do not matter, with those posted daily by the Romney press office from serving and former members of Congress and state legislatures normally ignored. But that of Bush is more important, a popular figure in the Republican party and one who would have been a candidate this year, held back only by the lingering unpopularity of his brother, George W Bush. He is frequently named as a potential runner in 2016.
The decision of Jeb Bush to come off the fence after Illinois is a recognition that senior figures have come round to the view that Romney is going to the eventual winner.
Romney, welcoming the endorsement, said: "Jeb Bush is synonymous with good government and with conservative policies that yield results. He has long demonstrated an outstanding ability to bring people together. I therefore take tremendous pride in having earned his endorsement. This is a key moment in the presidential contest."
He added that he would be relying on Bush for advice during the campaign against Barack Obama in November.
Romney's rivals played down the significance. Alice Stewart, Santorum's spokeswoman, told MSNBC: "We're doing this without the big-named endorsements, without the establishment endorsements. Rick is out there to get the endorsement of the American people and he is doing very well doing that."
Although there are 23 contests still to go, the overwhelming majority of these suit Romney better than his main rival Rick Santorum. Illinois was effectively Santorum's last chance to alter the course of the race and he not only lost but lost by a double-digit margin.
One of his senior campaign staff described as insurmountable the gap between himself and Santorum in terms of delegates to the party convention in Florida in August where the Republican nominee will be formally chosen.
The sense of weariness was picked up in exit polls in Illinois, with about 30% of voters saying they would prefer to see the race over, even if it meant their candidate did not win.
Romney, after beating Santorum by only narrow margins in states such as Ohio and Michigan, finally won the unqualified victory he had been looking for, beating Santorum by 47% to 35% in Illinois. His other remaining rivals have faded from the race and this was reflected in their votes, with Ron Paul on 9% and Newt Gingrich on 8%.
In his victory speech on the outskirts of Chicago, Romney said: "It's time to say these words. This word: enough. We've had enough." His words were directed at Obama but may also have easily been directed at – or even meant for – Santorum.
Romney has resisted calling openly for Santorum to quit the race, allowing his wife Ann and his campaign staff to do so instead, arguing that a long race helps the Democratic party.
In spite of outspending Santorum in advertising in Illinois and other states by ratios of at least seven to one, with some estimates much higher, Romney's campaign chest shows no sign of diminishing. Newly-released campaign figures, required by law, showed he raised $12.5m in February, his best month for fundraising yet, the bulk of it from big donors. Only one in 11 dollars came from people donating $200 or less. Romney spent $12.3m in February, most of it on advertising.
Santorum, who has been fighting on a relatively small budget, took in $2.5m in February. He has been campaigning in an old-fashioned way, getting out and about talking with voters, surrounded by, until recently, a small team.
Santorum is out to keep the campaign going as long as possible to establish himself as the Republican candidate not for 2012 but 2016. Although he blames his failure to beat Romnney on the disparity in cash and the presence of Gingrich splitting the conservative vote, one of his biggest problems has been to expand support beyond the core of Christian evangelicals and social conservatives he attracted at the start of the campaign in Iowa.
Santorum opted to hold his election night party Tuesday in Gettysburg, Pennsylvania, rather than in Illinois, saying it was a tribute to Lincoln and the Gettysburg Address. But it was also the scene of the decisive battle of the Civil War, the turning-point.
Santorum, though, shows no sign of being anywhere close to pulling out. He is almost certain to win Louisiana at the weekend – Romney has failed to win a state in the deep south – but after that the calendar looks bleak for him, with a slew of contests on April 3 and then a three-week pause in the middle of the month that will drain even more energy from the campaign.
At his Gettysburg party, he was defiant: "We're heading to Louisiana for the rest of the week, then we're back here in Pennsylvania and we're going to pick up a whole boatload of delegates and close this gap and then on to victory."
Santorum, Gingrich and Paul cling to the idea that Romney will be unable to reach the magic number of 1,144 delegates, a majority of the convention. In that case, they argue it would have to be a brokered convention, with all the uncertainty and drama that would entail. Romney's Illinois victory makes that less likely.
Former Mississippi governor Haley Barbour, a senior Republican who commands wide respect within the party, said even if Romney was to fall short of the 1,144, he would still win the nomination.
"I think it's very unlikely we'll go to the convention with an open nomination," Barbour told Politico. "The most likely outcome is that somebody will have a hot streak in the next few weeks and will get to 1,144 by June. Even if they come close to 1,144, there will be such a coalescence around them that the party will pull around."
Jeb Bush 
, the former governor of Florida, announced his endorsement of Republican presidential candidate hopeful Mitt Romney yesterday. This follows Romney's win in the Illinois primary on Tuesday, where he beat Rick Santorum by 12 percentage points.

In a statement, Bush argued that "now is the time for Republicans to unite behind Governor Romney and take our message of fiscal conservatism and job creation to all voters this fall". He also stated that he believed Romney to be "a leader who understands the economy, recognises more government regulation is not the answer, believes in entrepreneurial capitalism and works to ensure that all Americans have the opportunity to succeed".

Romney welcomed the endorsement and stated that it was a "key moment" in his campaign for the presidential candidacy: "Jeb Bush is synonymous with good government and with conservative policies that yield results. He has long demonstrated an outstanding ability to bring people together. I therefore take tremendous pride in having earned his endorsement."

Fundraising figures have been released for February: Romney raised 12.5 million during the month, and spent $12.3 million on advertising. In comparison, Santorum raised $2.5 million in February. The next primary will take place in Louisiana on Saturday, followed by primaries on April 3 in Wisconsin, Maryland and the District of Columbia. In Wisconsin, Romney is reported to be spending $2 million on television adverts compared to Santorum's $50,000.