BERLIN (Reuters) - German Chancellor Angela Merkel has said she will not seek re-election as leader of the center-right Christian Democrats (CDU) at a congress in December. Merkel, 64, also ruled out running for a fifth term as chancellor in 2021.

FILE PHOTO: Annegret Kramp-Karrenbauer addresses a Christian Democratic Union (CDU) party congress in Berlin, Germany, February 26, 2018. REUTERS/Hannibal Hanschke/File Photo

Several CDU politicians have announced bids to succeed Merkel as party leader. Here are some facts about the candidates who could step into her shoes:

THE MINI-MERKEL

Annegret Kramp-Karrenbauer, 56, was named by Merkel herself in February as CDU secretary general - a move seen as the first step in a succession plan.

Dubbed a “mini-Merkel” by German media due to their sober political styles, Kramp-Karrenbauer was premier of the tiny state of Saarland on the French border from 2011 to 2018.

Her Catholic, western German background contrasts with Merkel’s Protestant, eastern roots. While socially conservative and known for opposing gay marriage, Kramp-Karrenbauer is also a strong supporter of the minimum wage and workers’ rights.

In an attempt to distance herself from Merkel and her leadership style, Kramp-Karrenbauer has said the CDU will need to regain some passion if it wants to attract younger voters.

Sometimes known as AKK, she is the daughter of a teacher for mentally handicapped children, and is married to a mining engineer, with whom she has three children.

About 19 percent of Germans view Kramp-Karrenbauer as a good successor for Merkel, according to a poll conducted for Spiegel Online by the Civey institute.

THE CRITIC

Jens Spahn, 38, has become one of Merkel’s most outspoken critics within the CDU since her decision in 2015 to welcome more than a million refugees, mostly Muslims from war zones in the Middle East.

He positions himself as a politician from Germany’s rural northwest who is skeptical of urban liberals and the globalist elite.

In an attempt to rein Spahn in, Merkel this year named him health minister - a thorny portfolio that brings a lot of work and few headlines.

A member of the lower house of parliament since 2002, Spahn has been praised as a rising star for years by senior conservatives such as former finance minister Wolfgang Schaeuble.

However, his anti-immigration rhetoric at the height of the refugee crisis cost him sympathy among Merkel allies.

His public friendship with Richard Grenell, U.S. President Donald Trump’s ambassador to Berlin, has also alienated some conservatives who dislike Trump’s populist style.

Like Kramp-Karrenbauer, Spahn is a Catholic but, despite the church’s opposition to gay partnerships, he is married to Daniel Funke, a senior journalist at the glossy magazine Bunte.

The Civey poll showed Spahn with just six percent support.

THE OUTSIDER

The most popular candidate, according to polls, is Friedrich Merz, 62, who was the first to throw his hat into the ring on Monday after news leaked that Merkel would not run again as CDU leader. He confirmed his plans officially on Tuesday.

Merz, a member of the CDU’s conservative wing, has coined the idea of a German “Leitkultur” (lead culture), with which he called on Muslim immigrants to assimilate and to adopt German values and traditions.

Thirty-four percent of Germans view Merz as the best successor for Merkel, the Civey poll showed.

He also is known for his proposal to simplify the annual tax return so that it could be written on a beer mat.

Merz is among the many conservative men who have seen their political fortunes dwindle under Merkel.

In 2002, Merkel pushed him out of his position as CDU parliamentary leader to cement her grip on the party, on her way to becoming chancellor in 2005.

A trained lawyer and ex-member of the European Parliament, Merz served in the German parliament from 1994-2009, and now holds numerous non-executive company board positions, including chairman of the German arm of the U.S. hedge fund BlackRock.

He is married to Charlotte Merz, a judge, with whom he has three children.