The existence of the filibuster rule is why laws need the support of 60 Senators to get passed. That supermajority of 60 is required to quash a filibuster and move a bill to a vote.
It isn’t often one party has 60 seats in the Senate. Thus the existence of the Senate filibuster keeps a bare majority from railroading most extreme measures through the Congress.
Democrats had talked about dumping the rule permitting filibusters, which they could have done with 51 votes. However two Democrat senators from purple states, Kyrsten Sinema (D-AZ) and Joe Manchin (D-WV), have indicated they won’t vote for such a rule change. And President Biden - a former Senator - is reported to share this view.
Thus, the Senate will fall back on the precedent set back in 2001 when this even split last occurred. Apparently, Mitch McConnell has managed to salvage something from the wreckage after all.
Therefore, Joe Biden can do some things with executive orders. He cannot, however, take actions which require the passage of laws unless several Republican Senators vote with Democrats to enact them.
If Biden chooses not to enforce existing laws, he can be sued by parties damaged by those choices. In fact, the AG of Texas is reported to be suing about Biden’s decision not to enforce certain laws dealing with illegal immigration and deportation.
