And the far-right AfD looks set to enter the Hesse regional government for the first time after securing 12 percent of the vote.
The result means the anti-immigration party, which entered the federal parliament for the first time last year, is now also represented in all 16 German regional assemblies.
The regional government in Hesse, which includes the financial hub of Frankfurt, is currently controlled by a coalition of Ms Merkel's CDU and the Greens, and the exit poll results suggest the two parties can continue governing.
But the preliminary results will pile pressure on the Chancellor's 'grand coalition' in Berlin, which is made up of the CDU, its Bavarian sister party the CSU, and the centre-left SPD. Express.
