German Chancellor Angela Merkel's conservatives expanded their support to 40 percent - the highest level since September 2015 - in a poll conducted by the Forsa institute for Germany's Stern magazine and broadcaster RTL.
The rival Social Democrats (SPD) were unchanged at 23 percent, while the pro-environment Greens gained 1 percentage point to 9 percent and the anti-immigrant Alternative for Germany (AfD) party was unchanged at 7 percent, Forsa said.
The far-left Linke party lost 1 point to 9 percent, and the pro-business Free Democrats dropped 1 percentage point to 7 percent, in the poll of 2,502 eligible voters that was conducted on June 19-23.
It showed Merkel's Christian Democrats at their highest support level since September 2015, shortly after Merkel's decision to open the doors to more than 1 million migrants, mostly from the Middle East and Afghanistan.
Forsa said 52 percent of those polled would back Merkel for a fourth term if the chancellor were elected directly, a drop of 1 percentage point, compared with an unchanged 22 percent who would back SPD leader Martin Schulz, the former president of the European Parliament.
Whoever wins, we lose. I want the old Germany back