Anti-Trump Republican delegate Ken Cuccinelli told reporters he escorted Cruz's wife, Heidi, off the floor out of concern for her safety following her husband's speech.

Cruz, who came in a distant second to Trump in the race for the nomination, stopped short of endorsing Trump after a bitter and personal campaign and mentioned him only once, drawing boos and repeated chants of "We want Trump."

Cuccinelli, a former Virginia attorney general, said: "When the speech ended, there was an ugly crowd behind us."  A witness said one person shouted: "Goldman Sachs" at Heidi Cruz in reference to her employment at the investment bank.

Cruz began his speech saying, "I want to congratulate Donald Trump on winning the nomination last night." Later in the speech, he urged, "Please, don’t stay home in November. Stand, and speak, and vote your conscience, vote for candidates up and down the ticket who you trust to defend our freedom and to be faithful to the Constitution."

Some critics saw the appeal for people to vote their conscience as a vote of no-confidence in Trump. Republican strategist Eric Fehrnstrom, who is not affiliated with any campaign, tweeted, "'Vote your conscience' was the rallying cry of the Never Trump movement. For Cruz to bring that message into #RNC hall was a colossal error."

"It's taken me about 30 minutes to calm down and stop shaking with anger," said Erik Layton, an alternate delegate from California who had shouted, "Go home" at Cruz after his speech. "I just don't know why Cruz did this. It baffles my mind."

Trump, 70, a businessman and former reality TV star who will represent the party in the Nov. 8 election against presumptive Democratic nominee Hillary Clinton, made his entrance to the convention hall near the end of Cruz's speech, applauding Cruz's remarks but, by his appearance, drawing attention away from his former rival.

In a tweet after the convention adjourned for the night, Trump wrote that Cruz broke a promise they both had made to endorse the party's White House choice.

"Wow, Ted Cruz got booed off the stage, didn't honor the pledge! I saw his speech two hours early but let him speak anyway. No big deal!" Trump wrote.

During the campaign for the party's nomination, Trump insulted Cruz's wife's looks and suggested the Texan's father was with John F. Kennedy’s assassin just before the president was shot in Dallas in 1963.

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