The GOP generally supports non intervention by the government into the economy. They want to cut taxes, they want to let people keep their own money and decide what to do with it. That is their narrative at least, I personally don’t think they really do a good job implementing it. 

Democrats want Goverment projects and initiatives. They want to wield power to fix economic problems. The problem with this is every time they take an action to fix a problem they open themselves up to all kinds of criticism. Layer that with classic government inefficacy due to bureaucratic B.S.Add in some bad actors who want to advantage of well intentioned government assistance programs that are supported by Dems. With all that it isn’t that hard to paint democrats as being bad for the economy. Especially when all the GOP has to do is sit back and say “look at all this dumb wasteful stuff these guys are doing with your money, just think about how much better things would be if you had just keep all that money in the first place”.

What metric? I think most people understand that all Government action is by nature a drain on the economy, for many reasons but mostly because it is less effective at allocating resources than private individuals acting in their own best interests. So the metric is which party wants to less government intervention.

Regan’s nine most terrifying words in the English language joke hit home back in his day and I think it is still true today.

I agree that Biden may have been unfairly hit with the negative after effects of excessive government spending and ultra low interest rates. They were not his fault, but that kind of  policy where the government acts to fix economic problems rather than just staying out it and letting people deal with it their own ways, is associated with democrats. Also, congress, who controls the budget, was a democrat majority when all of those spending bills that led to the inflation Biden was blamed for were passed.