Job: Labour chairman and deputy leader, and Commons leader
Political Pedigree: Political survivor and campaigner on women's issues
Harriet Harman has long been one of the great survivors of modern politics.
She has steadily rebuilt her standing in the party after being sacked from Tony Blair's first Cabinet in 1998, her efforts culminating in winning the Labour deputy leadership earlier this year.
After becoming prime minister, Gordon Brown confirmed Ms Harman's return to the top flight of British politics by appointing her Labour chairman and the leader of the House of Commons. She is also equality secretary in the Cabinet.
But her future is once again looking uncertain, after it emerged she had accepted a £5,000 deputy leadership campaign donation "in good faith" from Janet Kidd.
Ms Kidd is an associate of David Abrahams, the property developer who gave Labour more than £600,000 via intermediaries - to huge criticism from the party's opponents.
The affair has provoked a row at Westminster.
Mr Brown - whose own leadership campaign turned down a £5,000 donation from Ms Kidd - has said he supports Ms Harman.
But, whatever happens, it is not the first time the MP for Camberwell and Peckham has faced a struggle for her career.
Ms Harman's close association with both Mr Brown and Mr Blair may have helped her in 1996 when she attracted heavy criticism from Labour ranks for sending her three children to selective state schools.
When Labour came to power in 1997, she entered the Cabinet as the social security secretary.
But she was sacked in 1998 following high-profile disputes with fellow minister Frank Field and backbench anger over cuts to lone-parent benefits.
On the backbenches, she remained loyal to the party leadership and returned to government in 2001 as the first female solicitor general.
After the 2005 election she took on the additional responsibility of constitutional affairs minister, with one of the most difficult briefs in Westminster - to reverse voter apathy and alienation.
Often portrayed as an ardent Brownite, she made much of the fact that she had worked with Mr Brown in the past during her deputy leadership campaign.
But as the wife of senior Transport and General Workers' Union official - and Labour Party treasurer - Jack Dromey, she has also has strong Old Labour credentials.
Sometimes described as "Labour's "in-house feminist", Ms Harman has long campaigned for more women MPs and for more family-friendly policies.
She has stressed her belief that there needs to be a woman at the top of government.
During the deputy leadership contest, Ms Harman said she alone could broaden the party's appeal at the next election, helping it to win back voters in Middle England.
At one point she described herself as the "Radio 2" to Gordon Brown's "Radio 4".
She has been an MP since Labour's most radical days in 1982.
Whether the great survivor can deal with the latest blow to her standing is the question many Westminster commentators are now asking.