Assuming Republicans lose none of their own seats — the only possibilities are the one held by Sen. Mitch McConnell (R-Ky.) and the open seat in Georgia — and win the two Democratic seats where they are clear favorites right now (South Dakota and West Virginia), that would leave them needing four more pickups to win the majority.

To get there, they would need to win two-thirds of the remaining Democratic seats in jeopardy: open seats in Iowa and Montana as well as those held by endangered incumbents in Alaska, Arkansas, Louisiana and North Carolina.

Neither of the open seats looks like a great chance right now — there’s no GOP candidate in Iowa, and it’s likely that popular former governor Brian Schweitzer (D) runs in Montana — which would mean that to get the majority, Republicans would need to beat all four targeted incumbents. Possible, but not probable.

Still, developments over the first few months of the year have worked in Republicans’ favor.