I didn't follow US politics as closely back then - were Democrats in better shape after their comprehensive defeat in 2004? Then, just as now, they had been beaten summarily by a Republican opponent who they considered boorish, stupid, authoritarian and an all-around insult to their intelligence. Then, just as now, they had no clear leader and no clear policy path forward.
What bailed them out back then was that GWB's second term was imploding onto itself. As time went on, it became clear that GWB and the GOP in his image were wrong on just about every issue. This time around, they are the ones who are wrong on just about every issue, which is the only reason why a deeply flawed candidate like Trump was able to defeat them so decisively to begin with.
So, basically, their only hope is for the economy to turn sour or for Trump to really overplay his hand.
Well if we run the historical numbers for comparison

Gallup's last poll was 38-56 in November just after the election. CNN put it at 29-54 in their latest poll, while Quinnipiac last month had 21-68 but had specified 'democrats
in congress.
I did a lot of digging around to see if I could find even two polls that hit the same time periods with democrats but jesus everything I look at is a total scattershot of different times, different topics. Quinnipiac in nov-dec only asked about Biden in specific for example
Now maybe the Gallup number will be higher than 21-28, but expecting something around 33-57 is probably reasonable.
So yeah that's by far the worst the democrats have ever polled in history, even before Trump was elected the first time and Obama was floundering. After their defeat in 2004 they were still ~50% favorable, and even just before their defeat in 2000 they were nearly 60% favorable.
Republicans "in congress" hit 45% in the last quinnipiac poll, which is actually their record high this century- again the 'in congress' really deflates perceptions.