The poll found that the Greens had 27 percent of the support, which is just a one point lead ahead of Ms Merkel’s conservative CDU/CSU bloc. Meanwhile, Ms Merkel’s Socialist SPD coalition partners plummeted to an all-time low. The poll asked voters which party they would back in a national election.
The poll reinforces a trend which saw the Greens surge past the SPD into second place in the European elections a week ago.
However, the Christian Democratic Union of Germany party (CDU) was down by two points.
The SPD, which is one of Europe’s flagship centre-left parties, was down by five points to 12 percent.
The SPD’s disappointing result puts them just a single point ahead of the far right Alternative for Germany party (AfD).
The nation’s pro-business Free Democratic Party (FDP) stood at just 8 percent.
The nationwide poll was conducted from May 27-31 by Forsa on behalf of German broadcasters RTL and itv.
Ms Merkel’s conservatives won last week’s European election with 28.9 percent on the vote.
However, their vote share result was down seven percent from five years ago.
The Greens with 20.5 percent beat the SPD who came third with just 15.8 percent of the vote.
Forsa executive Manfred Guellner told RTL: “The Christian Democrats and the SPD appear to have ignored a shift observed during regional elections in the states of Hesse and Bavaria, which showed that voters are moving from the liberal centre toward the Greens.
“Both major traditional parties have emphasised the importance of the environment in the aftermath of the European elections, but this only appears to have benefited the Greens.”
The CDU and SPD parties their worst result in European election history.