Rainer Candidus Barzel was born in 1924 in Braunsberg, East Prussia, now part of Poland. He was first elected to parliament in 1957, after serving as an advisor and speechwriter for Karl Arnold, the premier of North Rhine-Westphalia.

He then served as chairman of the CDU from 1971 and 1973 and ran as the CDU's candidate for Chancellor of Germany in the 1972 federal elections, losing to Willy Brandt's SPD.

The 1972 election is commonly regarded as an indirect referendum on Chancellor Brandt's Ostpolitik, or more open policy toward the eastern bloc, which called for normalized relations with the GDR and the USSR. Barzel was vehemently opposed to it, fearing that it might cement the permanent division of East and West Germany.

In May 1972, an attempt by Barzel and the CDU/CSU to call a motion of no confidence against Brandt's government failed by two votes. It emerged after German refunificaiton that some members of parliament had been paid off by the East German secret police, the Stasi, likely leading to the failure. Had the motion succeeded, Barzel would have succeeded Brandt as Chancellor of Germany.

Barzel served as Minister of Intra-German Relations (1982-1983) in Helmut Kohl's cabinet, and as President of the Bundestag (1983-1984).

He resigned from that post in 1984 after being accused of entanglement in a financial scandal known as the Flick affair.