Will ‘candidate quality’ doom Republicans’ Senate hopes?

Fresh doubts about the Republican Party’s chances of winning Senate control in midterm elections are being fueled by a slate of first-time candidates struggling to find their footing against seasoned Democratic competition.

Initial projections suggested a red tidal wave might sweep Republicans to power in November, ousting Democrats from Georgia to Washington state and New Hampshire to Arizona. With Labor Day and the homestretch of the fall campaign approaching, the GOP is suddenly fighting to defend seats in red states like Ohio and swing states like Pennsylvania. The culprit? Candidates endorsed by former President Donald...