Steinmeier, chosen Sunday to carry his Social Democrats' banner into the 2009 general election, has spent much of his career out of the spotlight.
The untested challenger to Chancellor Angela Merkel - he has never run for public office - is the affable but guarded protege of her charismatic predecessor Gerhard Schröder, who made Steinmeier one of his closest advisors during his seven years in power.
Steinmeier served as chief of staff in Schröder's centre-left government, coordinating the security services and shaping the Agenda 2010 package of economic reforms - the unpopular centrepiece of the administration.
He emerged from the shadows after the inconclusive 2005 general election, when Schröder put him forward as his candidate to take over the foreign ministry in negotiations on the formation of a "grand coalition."
A lawyer with a cautious streak, Steinmeier finds it difficult to speak in media-friendly soundbites, preferring measured statements with elliptical German sentences that end far from where they started.
He more resembles a civil servant than a glad-handing politician, and his charm works better in smaller, relaxed contexts where admirers say his dimpled smile and genuine interest in people can be used to the fullest.
A born diplomat, Steinmeier's softly-softly approach has led some to wonder whether he has the killer instincts needed on the political stage. Even supporters admit that taking on the high-flying Merkel may turn into a kamikaze mission on behalf of the party.
Born January 5, 1956 in a small town in Lower Saxony, Steinmeier was known on the football field as an efficient "all-rounder" who could play any position with ease and work well within a team.
The same qualities led Schröder to take him under his wing, first as media advisor when he was premier of Lower Saxony and later as a state secretary at the Chancellery until becoming chief of staff in 1999.
He took over the foreign ministry in November 2005, and has had, time and again, to defend his remit against encroachment by Merkel. They have clashed openly on Germany's approach to Russia and China, with Steinmeier warning against alienating either country with too strident criticism.
The number-two dismissed the chancellor's popular decision to meet last September with the Tibetan spiritual leader the Dalai Lama - to the ire of Beijing - as superfluous "windowdressing."
Steinmeier has also placed an emphasis on cultural diplomacy as a means of deepening Germany's ties abroad and frequently invites painters, musicians and novelists to accompany him on official visits abroad.
His profile grew again in 2007 when he became vice chancellor when a party general, Franz Müntefering, stepped down to care for his ailing wife. Married with a daughter, Steinmeier is protective of his private life.
Only recently has he started giving the kinds of interviews to celebrity magazines that allow potential voters to get to know a politician as someone with whom they might want to have a beer.