Order all the 2024 Senate races by the Democrat's margin of victory (i.e. % D vote - % R vote).* Which Senate race is the one that would give Democrats their 50th seat?

Here's an example:

• Democrats win all seats considered Solid D, plus MD, AZ, NV, PA, WI, MI, by a large margin. (This, plus the D seats that aren't being contested, brings them to 48 seats.)

• Republicans win all seats considered Solid R by a large margin. (That's 48 seats.)

• The remaining 5 seats are: OH (D+2), MT (R+4), TX (R+5), FL (R+7).

• Since Montana is the 50th seat by Democratic margin of victory (at -4), the market would resolve to "Montana".

Just for the purpose of reducing ambiguity, I will ignore deaths and resignations in the Senate. For example, if a Republican senator dies in a state with a Democratic governor (and so their replacement is likely to be a Democrat), that will not affect how this market gets resolved.

Note that I'm asking about the 50th seat -- that is, the seat that would give Democrats the majority, were they to win the (vice) presidency. That's because I think it's very likely that Democrats win the vice presidency conditional on the Senate being close enough for this question to matter.

*People count as the party they're associated with, e.g. Bernie Sanders is a Democrat.