Ukraine has the potential to be a thriving, prosperous nation. It has huge tracts of fertile “black earth” that have traditionally produced large grain surpluses. It inherited a well-educated workforce and a high technology base. It has coal reserves and heavy industries that have proved innovative, in some cases, in adapting to a post-Soviet world. Yet Ukraine has consistently failed to live up to its cherished independence. It spent the first decade resisting market reform. It allowed corruption to get a fatal grip on the state apparatus. And its politicians frittered away goodwill in profiteering and rancorous intrigue.

Once again, the country has reached a political impasse. President Yushchenko’s decision to dissolve Parliament and call for new elections next month has met furious opposition from Viktor Yanukovych, the Prime Minister, who called it a “fatal error” and has threatened to challenge it in the Supreme Court. His Government refuses to resign, and parliamentarians will not quit. After eight months of a dysfunctional administration, with the two rivals sniping at each other, Ukraine again stands on the brink of a constitutional crisis. Protesters have been massing in public squares. Two and a half years after the Orange Revolution, there is a grim sense of failure.

The root of Ukraine’s problems lies in the deep fracture — cultural, linguistic and religious — running through the country. Eastern Ukraine, where Mr Yanukovych musters most of his support, speaks Russian, is largely Orthodox and looks east; western Ukraine is the cradle of Ukrainian nationalism, acknowledges papal authority and feels closer to Poland than Russia. On top of these historical differences, which were exacerbated by Stalin’s persecutions and the Second World War, are the rivalries and divisions of Ukraine’s postSoviet turmoil — the botched privatisations, the emergence of criminal and oligarchic elites, the unholy alliances between politicians and business monopolies.

Neither politician can claim the moral or political highground. Mr Yanukovych’s corrupt attempt in 2004 to steal the presidential election, marred by the open intervention of Moscow on his side and the attempt to poison Mr Yushchenko, cemented the determination of demonstrators to continue their protests. Their Orange Revolution forced an election rerun that brought welcome change. Mr Yushchenko, however, has proved a vacillating leader, unclear how to control his headstrong first Prime Minister, Yuliya Tymoshenko, unable to root out corruption, and rash in promising faster and closer links with Nato and the European Union than either organisation was willing to envisage. His presidency has been marked by frequent political crises — a split with Mrs Tymoshenko and a parliamentary defeat by Yanukovych supporters — as well as poor relations with a suspicious Russia, which demanded an extortionate rise in gas prices in 2005.

The uneasy coalition with Mr Yanukovych has clearly collapsed. The stream of defections to the Prime Minister’s party has raised Mr Yushchenko’s fears that his rival was trying to build up enough support to override vetoes and side-line him. East and West see the dangers: Moscow and Brussels have called for calm and compromise. It is a call the squabbling politicians should heed for the sake of their long-suffering country.