German Chancellor Angela Merkel’s conservative Christian Democrats (CDU) are considering an increase in the top income tax rate as part of talks to forge a new coalition government, the daily Bild reported on Thursday.

Raising the tax on the wealthy was at the heart of the election campaign manifestos of the main opposition Social Democrats (SPD) and the Greens, two potential coalition partners for Merkel.

CDU General Secretary Hermann Groehe raised the idea as a possible concession to either the SPD or the Greens during internal CDU talks, Bild reported, though Groehe promptly denied saying any such thing.

Agreeing to the hike would represent a U-turn for Merkel’s government, which attacked the opposition tax plans throughout the run-up to Sunday’s election. Analysts have predicted the CDU might concede the point as the price to win a coalition deal.

Merkel’s Finance Minister Wolfgang Schaeuble also did not rule out tax hikes for top earners in comments made on Wednesday.

The CDU and its Bavarian-based Christian Social Union associate party remained the biggest political bloc in the lower house of parliament, the Bundestag, after the election but they still need to find a coalition partner to form a government.

According to Bild, in return for agreeing to increase the top tax rate, Groehe said the SPD would have to allow a CDU-backed law abolishing so-called bracket creep in the tax system to pass the upper house of parliament, the Bundesrat.

The opposition parties at present control the Bundesrat, which represents Germany’s 16 states.

Groehe issued a statement, saying: “This report is untrue. Our election policy is still in force. We oppose tax increases. We have a strong mandate from a very good election result to fight for our stance.”