The open-seat U.S. Senate contest in New Hampshire between Democratic Representative Chris Pappas and Republican John Sununu, rated a toss-up by multiple forecasters, anchors trader expectations for midterm turnout in the 650,000–800,000 range. Recent polling showing single-digit margins or statistical ties has heightened uncertainty over independent and base mobilization ahead of the September 8 primaries. New Hampshire’s above-average historical midterm participation, driven by high-propensity voters and strong candidate name recognition, supports elevated but variable totals compared with less competitive cycles. Primary results, national environment shifts, campaign spending surges, and Election Day weather on November 3 could separate the tightly bunched 500K–800K+ buckets by altering same-day versus early voting patterns.