On the ballot this year are 34 Senate seats. Democrats start with a disadvantage. They are defending 23 of those seats. Republicans are defending just 11.
To take over the Senate, Republicans do not need to do much. They need either a net gain of 1 seat if they also win the White House (and with it the ability to break ties), or a net gain of 2 seats if they don’t win the White House.
The most likely flip. In West Virginia, Democrat-turned-independent Joe Manchin’s retirement has opened up a seat that almost certainly will flip to Republican. (The Cook Political Report rates this likely a “Solid Republican” seat now, meaning it is nearly a sure thing that the GOP wins it.)
Yes, by organizing at the grassroots level in Texas, Wisconsin, North Carolina, Maine, and Georgia so that they send two blue Senators to Congress every single year. Vote totals in those areas are close enough to overcome the GOP’s structural advantages, but it will require a ground-up operation that bridges the divide between different coalitions on the left and builds a deep bench of community-connected candidates with good name recognition.