Even if they win a perfect split in the senate, with Harris breaking ties, they won't have "a mandate". They would have to tread carefully not to lose the votes of senators in conservative-leaning states. This certainly constrained the ACA we got.
We've hit a point where most blue states have two Democratic senators, most red states, two Republicans. Montana with Tester and West Virginia with Manchin are the only two red states that come to mind with Democratic senators since Jones lost in Alabama.
The GOP has Collins in Maine, Toomey in Pennsylvania, Johnson in Wisconsin, all three has been blue states for quite a while. Then Ohio is split, Brown and Portman, but Ohio is a swing state. Arizona now has two Democratic senators, I almost forgot about them.
Tester has pretty much followed the Democratic Party line, Manchin not so much. So you're worry will be probably Manchin. All the other states have two senators from the same party.
