He was a suave central banker and she a “gas princess”, a young politician desperate to make her mark. In 1998 Yulia  Tymoshenko, now Ukraine’s prime minister, said she knew her destiny lay with Viktor Yushchenko, who went on to become president.

“We understood that we are a team,” she said at that time.

It’s an assertion Yushchenko disputes — a clash of views that has defined this partnership since they overturned a Soviet-style leadership in the 2004 “Orange Revolution” and vowed a modern, Western future for Ukraine’s 47 million people.

Then they stood shoulder-to-shoulder — her revolutionary speeches firing up crowd after crowd, his more academic approach comforting those who feared she was reckless in her pursuit of power.

Now barely on speaking terms, their bickering over policy and outlook could force the former Soviet republic into the third parliamentary election in as many years.

But was their partnership only ever a marriage of convenience?

In 1999, the tough former businesswoman, dubbed the gas princess because of her success in the cut-throat world of post-Soviet energy dealings, became deputy prime minister for energy in Yushchenko’s government. She was dropped in 2001 and former President Leonid Kuchma launched a corruption case against her.

Some Ukrainian media say it was Yushchenko, fearful for his political future, who agreed to let her go, opening the way for corruption charges she says were fabricated by Kuchma.

Since then, many think the pair’s jealousies and mistrust of each other have made them squander the chance to steady Ukraine on a path towards Western integration and reform.

She lasted less than a year as Yushchenko’s first prime minister, sacked after they fell out over policy, particularly her calls for a broad review of 1990s privatisations.

Now sporting her trademark peasant braid, she is back as prime minister. Many analysts say Yushchenko is desperate to challenge her lead in the opinion polls, which suggest she would win a presidential election and gain seats in any vote for parliament.

Accusing her of dangerous populism that threatens to wreck the economy, Yushchenko has come out fighting. His office has accused her of being a traitor for not openly supporting Georgia after its brief war with Russia over South Ossetia.

He says she has driven the economy to the brink, with inflation reaching a record 30 percent earlier this year. His office says she is selling Ukraine out to the Russians to ensure Moscow’s support for the election.

But she denies all charges and is trying to convince her doubters that she can be pragmatic.

She has called for Yushchenko’s Our Ukraine party to return to the ruling coalition after he said the government had collapsed — a departure from her usual fiery stance which is bound to antagonise Yushchenko even further.

This battle of wills looks set to run.

By Elizabeth Piper, Reuters