In Arizona and Nevada, Republicans’ path to victory appeared to narrow, though both races remain close. The G.O.P.’s odds of success are greater in the House.
As candidates made their closing arguments on Sunday, Democrats braced for potential losses even in traditionally blue corners of the country while Republicans predicted a red wave.
Senator Catherine Cortez Masto is trying to hold off her Republican rival, Adam Laxalt, as both parties shovel money into a pivotal contest defined by two of this year’s top issues.
The contests are close in Arizona, Georgia, Nevada and Pennsylvania. Many voters want Republicans to flip the Senate, but prefer the Democrat in their state.