The reason they oversample democrats is because there are more registered Democrats than Republicans in general.
It is actually more accurate to oversample Democrats.
First, oversample by 10%???
Clearly there aren’t that many more Democrats.
Second, Rasmussen has the best track record and Rasmussen has been seperately sampling on the question of party identification. According to his tracking of this, Republicans actually surpassed Democrats around the time of the 2010 elections and since then, although I believe Dems have upticked slightly.
But at best for the Dems, they might lead by 1%, not 10, or they are in a dead heat with Republicans. Best case for us is that we are still ahead of them like we were in 2010 and the aftermath.
You must be referring to a long history of Dems clearly outnumbering Republicans, but that has changed as Ras has recorded.
We shall see.