They don't want to, but with enough voter pressure will if that's what it takes to stay in power. Unless there are candidates who are more left wing that have a realistic chance of wining elections at the state level it's probably necessary to work with what's in front of us, which probably means pressuring the dem representatives to move left. That'll take engaging with a significant portion of the electorate which is likely to be challenging, but probably the only way to slide the overton window left. I think the voters have to move first before the politicians follow, and they'll probably have to be cajoled as individuals rather than a party.