The Christian Social Union on Saturday elected Seehofer with 83.7 percent support. The lowest result previously since his first election as party leader in 2008 was in 2015 with 87.2 percent.
Seehofer has been under pressure since the CSU performed poorly in September's German election. It took 38.8 percent of the vote in Bavaria, 10.5 percentage points fewer than in 2013, rattling nerves in the party, which faces a state election next fall.
Earlier this month, Seehofer said he would step down early next year as Bavarian governor in favor of Markus Soeder, a younger rival, but remain as party leader.
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