Underscoring deep divisions at the Republican National Convention, U.S. Senator Ted Cruz of Texas was loudly booed on Wednesday night after he declined to endorse the party's presidential nominee Donald Trump and urged people to vote their conscience.

Anti-Trump Republican delegate Ken Cuccinelli told Reuters he escorted Cruz's wife Heidi off the convention floor in Cleveland out of concern for her safety.

"During the course of the speech more and more people were coming down closer and closer to Heidi and (Ted Cruz's father) Rafael. ... When the speech ended, there was an ugly crowd behind us. ... She was trying to leave," Cuccinelli said.

A witness said one person shouted "Goldman Sachs" at Heidi Cruz in reference to her employment at the investment bank.

RELATED: Ted Cruz full RNC speech

Cruz, who came in a distant second behind 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."

"I want to congratulate Donald Trump on winning the nomination last night," Cruz began.

Later in his 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."

Trump, 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 distracting the crowd from his former rival.

EXCHANGE OF INSULTS

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

Cruz, who as a Tea Party conservative in the U.S. Senate spearheaded tactics that led to a government shutdown over the federal budget, called the New York real estate developer a “serial philanderer” and a “narcissist” during the campaign.

A Cruz adviser who asked to remain anonymous said Cruz had anticipated a backlash from the crowd if he did not endorse Trump.

"We knew people were going to be mad if he didn’t say the words, but he congratulated him and called for unity behind common values. He expected people to not be thrilled about this" the adviser said.

Trump won the nomination on Tuesday with 1,725 delegates, followed by Cruz with 475 delegates,

In a speech a few moments after Cruz finished, former U.S. House of Representatives Speaker Newt Gingrich veered from his prepared text to defend Cruz.

“I think you misunderstood one paragraph that Ted Cruz, who is a superb orator, said. And I just want to point it out to you. Ted Cruz said you can vote your conscience for anyone who will uphold the Constitution. In this election, there is only one candidate who will uphold the Constitution,” Gingrich said.

"To paraphrase Ted Cruz, if you want to protect the Constitution of the United States, the only possible candidate this fall is the Trump-Pence Republican ticket,” Gingrich said.

Another Trump rival vanquished in the race for the party nomination, U.S. Senator Marco Rubio of Florida, spoke by video and praised Trump for his commitments to safeguarding national security, lowering taxes and appointing conservative Supreme Court justices.

"The time for fighting each other is over. It's time to fight for a new direction for America. It's time to win in November," Rubio said.