Is it a third rail for a Presidential candidate to blame Congress for not getting things done?

[Silent3]

I hated how much Trump tried to blame Biden for things that didn't get done largely because of Republican obstruction in Congress.

Eventually Biden finally, once, mentioned Republicans in Congress as a problem.

This isn't the first time I've noticed this phenomenon, however. This was true when Obama was running against Romney.

As much as it really is true that Republicans are to blame for blocking so much progress by Obama and Biden, I'm sure it was part of the Republican plan to not only make Obama look bad (and, as a bonus, make Biden look bad all these years later) cynically based on the idea that a President will look "weak" if he or she blames Congress for not getting things done.

And there's a lot of the public that's willing to go along with that, thinking that a President is supposed somehow magically talk Congress into going along with their plans, and if they can't accomplish that, they must not be a good President.