Or they think it will be. I think their perverted reasoning is to make the charges against the Obama administration appear to be the rot and then to say that Biden is rotten by connection.
They are smart in one way. Now, it will be reported as both candidates have serious scandals and investigations, etc. And they will say (we know this is completely false) that Trump has been completely exonerated and that is because Obama is guilty.
It is complete deceit. But it has worked well for them in the past. They shore up the base and bring in just enough "undecideds" to move the scales close enough so that they can steal the rest.
Unfortunately, it could work for them. I don't think it will be it could ... there is a long time between now and November 3, 2020. Time for them to spin their insane lies.