With the effective election of Mitt Romney as the Republican candidate, the US presidential election has started in earnest. The Republican primaries were an ideological war of attrition within the party between its right-wing — who were trying to get it to select a candidate with social and economic policies that would essentially make it unelectable — and more moderate, practical conservatives.

Romney's win means the Republican Party will now be able to start crafting an election platform that will have to marry the ideals of its core conservative supporters, with social policies that will appeal to the wider electorate and provide a boost to the economy. Managing these competing — even contradictory interests will not be easy.

But at least Romney can now start trying to heal the rift between the Republicans and key constituencies, like women, who were offended by the political positions adopted by Rick Santorum, his former rival for the nomination.

Romney can now also turn his attention, and financial resources, to taking on US President Barack Obama. It is perhaps too cynical to say that US elections can be "bought", but the financial resources of the campaigns will have a major impact on the final result.

While international affairs and its involvement in overseas conflicts will receive some attention, the main fight between Obama and Romney will be over the US economy.

Obama's campaign has been strengthened by some better economic news of late, but the recovery remains weak.

In short, not enough jobs are being created fast enough to guarantee that American voters will give Obama another term in office, even though, for now, he is ahead in some opinion polls.

But while Americans might like Romney's rhetoric of reducing government spending, they have shown little taste for the reality of cutting of entitlement and development programmes. As always, the fortunes of the candidates are tied with that of the US economy.