Such frequent, deliberate cursing by presidential candidates addressing campaign audiences in this election cycle seems to be without modern precedent. It is a striking departure for a party whose 2012 nominee, Mitt Romney, let fly expressions like “H-E-double-hockey-sticks” when he wanted to be puckish.

Republican officials have strained to adjust, questioning whether the moment will last.

“He does it because he needs attention and can’t control himself,” Stuart Stevens, who was Mr. Romney’s chief strategist, said of Mr. Trump. “Both are not qualities in demand in a president.”

Henry Barbour, a Republican National Committee member, said it was all “just part of this strange reality-TV era we are suffering through.”

Some milder adjectives appear to be bipartisan. In the first Democratic debate, Senator Bernie Sanders of Vermont memorably declared that America was tired of hearing about Hillary Rodham Clinton’s “damn emails.”