The CDU is now polling just one point behind the centre-left SDP, it’s main rival for the chancellorship. Ms Merkel is standing down as German Chancellor, with the CDU hoping to elect Armin Laschet as her replacement.
The latest survey, by the Allensbach Institute for Demoscopy, indicates the SDP’s lead has been cut to one percent.
The Social-Democrats are on 26 percent, down one, ahead of 25 percent for the CDU and their Bavarian sister party.
In third place the Greens gained 0.5 percent, to 16 percent whilst the liberal FDP increased its projection by one joint to 10.5 percent.
However, the far-right AfD has seen a reduction in support, which fell one point to 10 percent.
The survey was conducted on behalf of the Frankfurter Allgemeine Zeitung newspaper.
Ms Merkel has been campaigning for Mr Laschet, who her party hopes will succeed her.
She has appeared alongside her potential successor, along with Bavarian prime minister Markus Soder.
In January Mr Laschet, minister-president of North Rhine-Westphalia, was elected as the new CDU leader.
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She added: “It is clearer than ever that no political party is doing close to enough. But it’s even worse than that.
“Not even their proposed commitments are close to being in line with what would be needed to fulfil the Paris agreement.”
In July western Germany was struck by flooding, which killed 180 people, pushing climate concerns up the political agenda.
Ms Merkle has been German chancellor since November 2005, when she succeeded Gerhard Schröder.
She has played a key role in EU wide politics, such as with Brexit and the 2015-16 migrant crisis.
On Friday photos of Ms Merkle campaigning in the town of Marlow, in Mecklenburg-Western Pomerania, went viral.
They show her feeding a flock of Australian rainbow lorikeets, with three on each hand and one on her head.
At one point the chancellor was nipped by one of the birds, and let out a short screech.
The moment was captured by George Wendt, a DPA news agency photographer.
In 2016 Barack Obama, the former US president, said Ms Merkel had been his “closest ally” whilst in office.
Additional reporting by Monika Pallenberg.