JERUSALEM – The gray man of Israeli politics has turned into the invisible man. On the brink of becoming prime minister, Ehud Olmert has adopted the peculiar strategy of disappearing from the election campaign.

When most politicians are busy with rallies, photo-opportunities and press calls, Mr. Olmert prefers the sidelines.

According to one spokesman for the Kadima party, which Mr. Olmert leads and which is expected to cruise to victory next week, this is partly to save money. Another said it was because voters do not like being hectored.

But it might also be an acknowledgement that Kadima’s centrist message is still linked with his mentor, Prime Minister Sharon, who remains in a coma after a huge stroke in January.

The party’s web address remains www.kadimasharon.co.il and the image of Mr. Sharon, not Mr. Olmert, dominates its broadcasts.

“The leaders of the other political parties are talking too much in the language of the past, about promises that voters have heard many times before and have been disappointed about many times before,” one of Mr. Olmert’s spokesmen, Raanan Gissin, said.

To his critics, Mr. Olmert is an opportunist, to his supporters a visionary. Almost all Israelis accept he is a leader on the brink of an epoch-changing premiership for the Jewish state.

Previous prime ministers were drawn from a breed of war-hardened army officers or resistance leaders. Mr. Olmert belongs to a greyer class of careerist, who made his name as mayor of Jerusalem.

Mr. Olmert’s unique feature is his promise to fix the borders of a country that has not had a permanent, settled frontier since it was founded 58 years ago.

Although not as well known abroad as many of his predecessors, he is viewed in Israel as a politician with acumen and ambition. His only known vice is a fondness for Havana cigars although he is reported to be a fitness fanatic, jogging six miles most mornings, and a football fan, supporting Betar Jerusalem, a team with notoriously raucous and enthusiastic fans.

He was born in a small Jewish community in 1945 to parents who belonged to Irgun, the radical Zionist movement regarded as a terrorist group by the British. As a child, he is remembered as a talented student committed to Right-wing politics from an early age.

“He is fearless and cares only about Ehud Olmert,” Moshe Amirav, who worked alongside the teenage Mr. Olmert in the Zionist movement, Betar, said.

“In my book, that’s what makes great leaders; ambitious people determined to leave their mark on history by doing great things.” One of the greatest tests of Mr. Olmert’s views was when he met the woman he fell in love with and married, Aliza Richter, a Left-winger and fellow student at Hebrew University.

The couple have five children, one of them adopted, and Mr. Olmert was constantly challenged at home over his beliefs. He often joked how family discussions left him in a “minority of one.”

In 1973, he became the youngest member of the Knesset aged just 28 before combining a career as a lawyer with one as a politician.

Later he turned the fight against corruption into a national issue. An opponent he accused of graft committed suicide a week later.

The many accusations of corruption against Mr. Olmert himself therefore have an ironic twist. He has denied all wrongdoing and while at least one case was settled out of court he has not been convicted of any crime.

Along with other ambitious Right-wingers, he knew he had to build a power base.

This he did as mayor of Jerusalem between 1993 and 2003 where he encouraged Jewish acquisition of property in parts of the Old City and East Jerusalem claimed by Arabs.

His greatest achievement was to ally himself with Mr. Sharon, the Right-wing prime minister who dared to give up land where Jewish settlers are heavily outnumbered by Palestinians.

Whereas in the 1970s Mr. Olmert had voted against the transfer of Sinai to Egypt under the Camp David peace accords, three years ago he backed the much more controversial withdrawal from Gaza.

When Mr. Sharon was struck down, Mr. Olmert’s time had come.

Since January he has moved effortlessly into the role of acting prime minister, fully committed to Mr. Sharon’s plan to cede only those parts of the West Bank where settlers have no chance of outnumbering the Palestinians.

He has still not allowed himself to occupy Mr. Sharon’s large leather chair at the cabinet table, which has remained empty out of respect for the warrior.