MP for Makerfield since June 1987, Mr McCartney has been a frontbencher since 1992 and immediately joined the government at the trade department after the party's 1997 election triumph.
His close links with the unions helped him to bring Labour's flagship employment settlement successfully through the Commons. He was also able to put the minimum wage, for which he had long campaigned, on the statute book.
He moved to the Cabinet Office in 1999, taking on the government's campaign again drugs, an issue close to his heart after the death of his son following a heroin overdose.
He was appointed pensions minister after the last election. Mr McCartney is an extremely active MP famed for his withering attacks on the Tories in the Commons.