Support for Chancellor Friedrich Merz has fallen to its lowest level on record after his Christian Democratic Union, or CDU, lost ground to parties on its right and left in three state elections this fall, a poll released on Thursday found.

Only one in 10 respondents said they were satisfied or very satisfied with the chancellor’s work. It is the worst mark for any German leader since that survey began in 1997. The defeats came on both flanks: to the far-right Alternative for Germany, or AfD, and to the Left.

The bleakest result came on Sept. 20 in Mecklenburg-Western Pomerania, on the Baltic coast. Projections by the public broadcaster ARD gave the CDU 4.9 percent of the vote, the party’s weakest result in any state since World War II. It fell below the 5 percent threshold for seats and dropped out of the state parliament, the first time the party has failed to win representation in a German state legislature.

In Berlin, where the CDU had led the state government, the party lost nearly a third of its support and fell to about 20 percent, according to Deutsche Welle. Two weeks earlier, in Saxony-Anhalt, the AfD had routed the conservatives with a record 44 percent, the third state where the far right has finished first.

The chancellor has ruled out any change at the top. Minutes after the first exit polls flashed across German screens on Sept. 20, Mr. Merz appeared in a televised statement at CDU headquarters and declared that he was going nowhere. “It’s a disaster,” he said of the Mecklenburg-Western Pomerania result. “What needs to be done now requires backbone, steadfastness and patience. I will muster them — as party chairman of the CDU and, above all, as chancellor of our country.”