Actually, an RCV system may help the democrats, at least in the short term.

For the last couple of decades, the “spoiler” candidates generally take from the democrats more than the republicans. Last big spoiler third party that screwed the right was Perot that I remember. With RCV, then the ‘fringe’ votes can still be cast and democrats can work toward being the second choice of those hardliners. At least in the short term, it alleviates the need to actually compete for votes with candidates that are going to lose anyway.

Longer term, it may cause a viable third party or more to get some steam (attracting practical candidates that no longer see the need to be a D or R to get votes, the parties generally getting left alone by outside forces that find them not worth weaponizing), but I don’t think the politicians are too concerned on that long a time frame.