Standing in the Speaker’s Lobby just off the House floor, Representative Bill Pascrell Jr., Democrat of New Jersey, predicted that Mr. Boehner’s departure would make things harder rather than easier. “November and December are going to be like Dante’s ‘Inferno’ around here,” he said…

“A lurch to the right is suicidal,” said Gregory Slayton, a Republican fund-raiser who backed Gov. Scott Walker of Wisconsin in the presidential race before he dropped out a week ago…

Mr. Slayton, who called Mr. Cruz “a 45-state-loss prospect in a general election,” said the party needed to find a nominee “who can be a peacemaker and a bridge builder” between factions…

Mr. Zeidman said Mr. Boehner’s exit worried him a great deal because it might embolden the hard-liners in Congress.

“If we shut the government down, we’re dead,” he said.