Regrets? Delaware Sen. Chris Coons has a few—and not too few to mention. At the top of his list is his party’s decision in 2013 to blow up the filibuster for most presidential nominees.

“Many of us will regret that in this Congress,” a dejected Mr. Coons told CNN on Tuesday. “Because it would have been a terrific speed bump, potential emergency brake, to have in our system to slow down the confirmation of extreme nominees.”

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