Undercutting calls for Republican unity, Texas Sen. Ted Cruz stubbornly withheld his endorsement from Donald Trump as he addressed the GOP convention Wednesday night, instead encouraging Americans to "vote your conscience" in November.

Delegates on the floor implored Cruz to back the nominee, chanting Trump's name, then erupting in a chorus of boos when he ignored their pleas.

"Vote for candidates up and down the ticket who you trust to defend our freedom and to be faithful to the Constitution," Cruz said. While he backed some of Trump's policy proposals, including building a wall along the U.S.-Mexico border, he mentioned the GOP nominee by name only once.

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Cruz's decision to accept a speaking role at the convention but not explicitly endorse Trump was remarkable, and underscored the deep divisions still coursing through the GOP. While Trump has energized many Republican voters, others remain deeply skeptical of his unorthodox candidacy and divisive policy proposals.

The Republican convention: What you missed on Wednesday

Boos filled the convention hall in Cleveland as Cruz finished his prime-time speech. Cruz finished second to Trump in the delegate count and the two were bitter rivals during the primary campaign.

Cruz's wife was escorted off the floor as delegates booed.

Republican Ken Cuccinelli, the former attorney general of Virginia and a supporter of Cruz, told Reuters he escorted Heidi Cruz off the convention floor for her own safety.

The gulf between Trump running mate Indiana Gov. Mike Pence's hearty embrace of Trump and Cruz's refusal to do so is emblematic of the turmoil still roiling the GOP.

The low-key Pence, who describes himself as a Christian, a conservative and a Republican "in that order" later today the crowd he never thought he'd be standing on the stage at his party's national convention.

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He joked that Trump is so charismatic that he must have been looking for balance in choosing him.

Then he turned serious by framing the November presidential race as crucial to defining the makeup of the Supreme Court for the next 40 years.

The GOP vice-presidential nominee said voters must ensure that it's Trump picking the next high court justices to protect the Second Amendment, which covers the right to bear arms, "the sanctity of life" and other liberties.

Trump did get a boost from Wisconsin Gov. Scott Walker, one of the 16 Republicans whose White House dreams were vanquished during the primary. Still, Walker suggested he was driven as much by a desire to keep Democrat Hillary Clinton out of the White House as admiration for his party's nominee.

"Let me be clear: a vote for anyone other than Donald Trump in November is a vote for Hillary Clinton," Walker said.

Later, Republican stalwart Newt Gingrich said people should be terrified at the prospect of Clinton as president.

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The former House speaker says Clinton won't tell the American people the truth about the danger posed by Islamic extremists and that the price Americans would pay for electing Clinton would be what he calls the "loss of America as we know it."

Gingrich, a Donald Trump ally, argued that Islamic extremists are stronger than the Obama administration admits.

Trump's campaign hoped that by the convention's end, voters would look past the gathering's rough start, including the plagiarism charge involving Melania Trump's opening address. After 36 hours of denials, the campaign moved to put the matter to rest Wednesday, releasing a statement from a speechwriter who took blame for including lines from a Michelle Obama speech in the remarks.

Trump, who will address the convention Thursday night, cheered on the night's proceedings via Twitter. After Walker's remarks, Trump wrote, "Great speech!"

A day after Trump formally became the presidential nominee, some delegates at state gatherings around Cleveland where the four-day GOP convention is being held were still struggling to come to terms with their unorthodox new standard-bearer.

Iowa delegate Cecil Stinemetz called Trump "the worst nominee that we have put forward for the Republican Party in the history of the Republican Party" and said he didn't plan to return to the convention floor the rest of the week.

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Republican worries about Trump's preparedness for a general election battle with Democrat Hillary Clinton have only been reinforced during the convention. The campaign struggled to respond to plagiarism charges involving Melania Trump's Monday night address, finally releasing a statement Wednesday from a speechwriter who took blame for including lines from a Michelle Obama speech in the remarks.

Campaign officials see Pence's address Wednesday as an important opportunity to reassure the doubters. In a show of unity, he'll be introduced by House Speaker Paul Ryan, a lukewarm Trump supporter, and lay out his reasons for partnering with the celebrity businessman who is in many ways his opposite.

While Pence is expected to make the case that Democrat Hillary Clinton is unfit for the White House, officials said his speech will not be a full-throated takedown in the style of earlier speakers.

Cruz was harshly critical of Trump in the waning weeks of their primary battle, calling the businessman a "pathological liar" and "utterly amoral." He arrived in Cleveland with an eye on his own political future, holding a rally with hundreds of supporters who greeted him with chants of "2020" — suggesting Cruz's backers have no interest in seeing Trump become a two-term president.

Cruz was expected to continue sidestepping a formal endorsement of Trump during his convention remarks. Top Trump aide Paul Manafort said the senator would at least "suggest" he is backing the nominee, while other Republicans said Cruz would argue the importance of keeping Clinton out of the White House.

That message is sure to be well-received in the convention hall, where Clinton has been under constant attack. Speakers have painted an apocalyptic vision of America if she wins and have aggressively challenged her character. While Clinton has been a target of GOP ire for decades, the harshness of the attacks was still striking.

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Former GOP presidential candidate Ben Carson connected Clinton with Lucifer. New Jersey Gov. Chris Christie implored delegates to shout "Guilty!" in response to various accusations of wrongdoing. And for a third straight night, the crowd filling the convention hall Wednesday chanted, "Lock her up."

For at least some delegates, the negativity crossed a line.

"Certainly races can be won based on focusing on the opponent," said Sen. Bob Corker of Tennessee. "But I think we're at a place in our country's evolution where it's particularly important now, with all that's happened and the concerns that people have, for a positive vision to be laid out."

Trump has shown little concern for maintaining any modicum of political decorum. Yet Pence, the Indiana governor and Trump's new political partner, has spoken out against negative campaigning and was put on the Republican ticket in part to provide a temperamental contrast.

The Trump-Pence ticket was off to an awkward start, with some Republicans whispering that the businessman was gripped by last-minute doubts about his pick.

The campaign hoped for better imagery Wednesday. Pence and his family, along with Trump's adult children, greeted the billionaire as his helicopter landed by Cleveland's picturesque lakefront.

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"What begins in Cleveland will end in the White House, I'm convinced," Pence declared as they greeted a small group of supporters.