Overall, I think the Senator that is going to be hurt by this the most is Heitkamp. She has been behind in her race for a while now, but I still thought she had a good chance of retaining that seat. However after this whole Kavanaugh thing she has gone from a 2-3 point dog to a 9-10 point dog in my estimation. I'm pretty neutral on who ends up winning the Senate, but from an objective point of view it does appear that this whole ordeal has hurt the Dem's chances of controlling the Senate in November. A week ago, 538 had them with a 1 in 3 shot of flipping the Senate. Now its more like a 2 in 9 shot and the spread continues to get bigger every day. It has also hurt them a little bit in the race for the House, but I don't think it has hurt them enough for them to lose it. They are still going to flip the House in all likelihood.
It should be noted that all of this could change on a dime. 538 also suggested that whoever ends up on the "losing" end of this deal could end up using their loss to galvanize their base for the Midterms. So if Kavanaugh is confirmed we might see a legitimate bump in some of the elections, especially in the more traditionally blue areas. Don't think that is going to help Heitkamp though.