As primary season draws toward its close, the contest for Senate control is settling into a shape that favors neither party with ease. Democrats must convert four Republican-held seats into their own — a demanding but not inconceivable arithmetic — while Republicans find themselves in the unfamiliar posture of defense, protecting what they have rather than reaching for more. The primaries unfolding now are not merely procedural; they are the quiet machinery that will determine which candidates carry each party's hopes into November, and whether those hopes are grounded in reality or aspiration