The appointment of Hillary Clinton as US secretary of state will place a two-for-one power couple at the heart of Barack Obama's cabinet, which could tie the president-elect’s fortunes to the conduct of Bill Clinton, the former president.

There has been no formal announcement of Hillary Clinton’s new role but the appointment was said to be “firmly on track” after negotiations with Bill Clinton over his charitable and business affairs.

Although the former president last week gave Obama’s team of vetters the largely secret names of 208,000 donors to the William J Clinton Foundation, which covers his presidential library and the charitable Clinton Global Initiative, they may turn out to include some ticking timebombs.

Several US news organisations are digging for more disclosures of controversial allies such as Frank Giustra, the Canadian tycoon who accompanied Bill Clinton on a visit to Kazakhstan and subsequently clinched a $425m mining contract there.

“Among the questions being raised are: who is paying for his speeches and who is paying for the planes he is flying on?” said a source familiar with the investigations.

Bill Clinton, 62, is said to have agreed to restrictions on his paid speeches and his role at the foundation in an attempt to avoid future conflicts of interest. An ally of the Clintons insisted: “Bill has said publicly that he will do whatever they want. Not just with the Giustra stuff, but with the library, the foundation, the donors - he has demonstrated a willingness to go above and beyond.”

However, he will not forgo the lucrative lecture circuit. Last Sunday, even as his wife, 61, was pondering whether to accept the job and resign as New York senator, Clinton was in Kuwait City delivering a reported $500,000 speech, paid for by the National Bank of Kuwait, on the world financial crisis.

Hillary Clinton has been forced to write off the $13m she had lent to her election campaign and the family coffers will not be replenished by her public servant’s salary at the State Department. Jeff Gerth, the co-author of Her Way, a biography of Hillary, said: “The momentum for this appointment seems to be coming more from the Clinton side than the Obama side.”

If her appointment is confirmed, Hillary Clinton will join Obama, 47, on a high-profile “grand tour” of Europe that could combine three summits next spring. Gordon Brown is pressing to be the first western leader to receive Obama at a G20 economic summit in Britain, to be followed immediately by a European Union summit in Prague and a Nato summit in Strasbourg in April.

Obama’s allies are already concerned by the ability of the Clintons to upstage the president-elect after a week of leaks and nonstop “drama”, during which her friends confirmed the job offer ahead of Obama. One distinguished foreign policy expert predicted that “she’s going to be the mother-in-law you can’t get out of the house”.

Some of Clinton’s most ardent supporters are already speculating that she will triumph on the global stage while Obama will be bogged down by a collapsing economy that is beyond his power to rescue.

In his weekly radio address yesterday, Obama outlined a plan to create 2.5m jobs over the next two years by rebuilding roads and bridges, modernising schools and investing in green technologies.

With Clinton at the State Department, Obama is likely to appoint James Jones, the former Nato commander, as his national security adviser. That leaves top members of the Obama team out of the running for the most senior appointments, including Susan Rice, his foreign policy adviser, who was with him every step of the election campaign. One leading aide said: “I would hate to see everyone end up as deputies.”

Clinton has insisted she must have direct access to the president, rather than going through his national security adviser, and wants to appoint her own team at the State Department. She is likely to make the search for Middle East peace a priority after it eluded her husband.

Steven Clemons, a foreign policy expert at the New America Foundation in Washington, said: “Her top, top, top advisers told me, ‘She will animate things in the Middle East - she will deliver a Palestinian state. Gold-plated’.”

Obama is also close to announcing that Robert Gates, the defence secretary, will remain in his job, and Timothy Geithner, president of the Federal Reserve Bank in New York, will run the Treasury.

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