CLEVELAND — It was the biggest speech of Melania Trump’s life, and her husband, Donald, wanted it to be perfect.

The Trump campaign turned to two high-powered speechwriters, who had helped write signature political oratory like George W. Bush’s speech to the nation on Sept. 11, 2001, to introduce Ms. Trump, a Slovenian-born former model, to the nation on the opening night of the Republican National Convention.

It did not go as planned, and it has eclipsed much of the action at the party gathering in Cleveland, where delegates on Tuesday night formally nominated Mr. Trump for president.

The speechwriters, Matthew Scully and John McConnell, sent Ms. Trump a draft last month, eager for her approval.