U.S. flags at the Washington Monument, the dome of the U.S. Capitol can be seen in the background. Sebastian Gollnow | Picture Alliance | Getty Images Control of the U.S. Senate in this year's midterms remains a tossup just over six months from election day, according to traders on prediction markets platform Kalshi.  Traders give both Republicans and Democrats a 50% chance of winning control of the upper chamber.  While traders have Democrats as favorites to flip control of the House of Representatives, odds in the Senate have narrowed in 2026.  Republicans saw their odds of maintaining their majority fall from 67% on January 1 throughout that month and February, but the declines intensified in March as traders priced in the political consequences of the U.S.-Iran war.…