Merz: Will help drive down both AfD and FDP, also might be able to get AfD to agree to abstain on all bills that the government could fall over. On the other hand pretty much kills any chance the Greens or SPD will agree to work with him. Also might drive some centrists over to the Greens or SPD
Friedrich Merz has recently taken a hard left turn, putting the AfD on par with the NSDAP and decribing them as "openly national socialist" while publicly praising the Greens' merits as a potential future coalition partner for the CDU. Of course that's also part of an opportunistic ploy to steal votes from AKK. Could possibly backfire on him since it's maybe a bit too obvious that he's just trying to sell us bullsh**t here.
That will likely hurt him as while people like politicians who are open minded and willing to change views if evidence shows original ideas don't work, they hate opportunists who change their views just because they think it will help them politically. In his case it looks like he is the latter not the former.