The Republican convention dissolved into boos and open conflict in prime-time view when Donald Trump's fiercest primary rival took the stage Wednesday night and refused to endorse him as the GOP nominee, overshadowing the national introduction of vice presidential hopeful Mike Pence.
The powerful getting-to-know-you speech by Pence, Indiana's governor, was intended to cap off the program and right a convention that has veered repeatedly off course.
But Sen. Ted Cruz — or "Lyin' Ted" as Trump branded him during their caustic primary fight — rekindled the turmoil of the first two days when he declined to capitulate to his erstwhile foe and, as tradition and protocol dictate, stand behind Trump.
The scene, which seems destined for repeated television replay in the days to come, may become one of the defining moments of the convention, which has been torn by much of the discord that marked the party's long and brutal nominating contest.
Cruz took the stage to a thunderous ovation and a cowboy-hat-waving salute from his fellow Texans, and the cheers persisted as he called for the defeat of Democrat Hillary Clinton.
"Citizens are furious, rightly furious, at a political establishment that cynically breaks its promises and ignores the will of the people," he said, acknowledging Trump's political-outsider appeal. "We have to do better. We owe our fallen heroes more than that."
But the mood swiftly turned against Cruz at the speech's climax, when it was clear he was not only withholding his endorsement, but also leaving room for voters to abstain from backing the nominee.
"To those listening, please, don't stay home in November," Cruz said. He paused dramatically, eliciting loud boos.
"If you love our country and if you love your children as much as I know you do, stand and speak and vote your conscience," he said. "Vote for candidates up and down the ticket who you trust to defend our freedom and to be faithful to the Constitution."
The phrase "Vote your conscience," a rallying cry for the conservative anti-Trump movement, appeared to infuriate the crowd, which chanted at Cruz to endorse Trump.
Former House Speaker Newt Gingrich, a staunch Trump ally who openly campaigned to become his running mate, mounted an unscripted defense just minutes after Cruz left the stage, praising "the extra effort Donald Trump has invested in bringing the party together" by allowing his formal rivals to speak.
He then slyly turned Cruz's snub into an endorsement.
"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 loud cheers. "So, 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."
Preceding Cruz was Florida Sen. Marco Rubio — whom Trump disparaged as "Little Marco" when they fought for the nomination — who opted against making his concession in person.
Appearing in a brief recorded message played on a giant screen above the stage, Rubio referred to his fight against Trump with a wan smile. "After a long and spirited primary, the time for fighting is over," Rubio said. "It's time to come together. It's time to win in November."
A third former rival, Wisconsin Gov. Scott Walker, scarcely mentioned the nominee in his speech, and his stiff body language suggested a lack of enthusiasm.
Instead, Walker articulated his own small-government vision of conservatism, growing the most animated when he recounted his battles with labor unions at home and warned of the perils of a Clinton presidency.
"Let me be clear: A vote for anyone other than Donald Trump in November is a vote for Hillary Clinton," Walker said. Like Cruz, he warned the discontented against sitting out the November election, but made a more definitive pitch for Trump. "We can't wait four years to get 'em next time. The consequences are too great."
Even as upheaval erupted on the convention floor, Trump set off what is almost certain to be another major rift with the party's foreign policy elite, saying in an interview with the New York Times that, as president, he would not necessarily abide by U.S. treaty obligations to defend the three Baltic nations if they were invaded by Russia.
He would defend those countries from attack only after reviewing whether they "have fulfilled their obligations to us," the paper quoted him as saying.
The evening's chaos distracted from Pence's strong introduction of himself as "a Christian, a conservative and a Republican, in that order," with homespun stories about his family and a self-deprecating joke about his place on the ticket next to the larger-than-life Trump.
"He's a man known for a large personality, a colorful style and lots of charisma," he said. "So I guess he was just looking for some balance on the ticket."
But Pence in fact proved himself a valuable second, commanding the crowd as he praised the nominee and attacked Clinton with a far more disciplined style and traditionally conservative message than Trump.
"You have nominated a man for president who never quits, who never backs down, a fighter, a winner," Pence said. "Until now, he's had to do it all by himself against all odds. But this week, with this united party, he's got backup."
Trump arrived in this convention city Wednesday afternoon in a dramatically staged scene that was marred, despite his best efforts, by continued controversy and an emphatically negative reception from party holdouts.
Touching down at a lakefront airport on a cloudless afternoon, Trump switched to a helicopter stamped with his name and twice circled downtown before stepping off to a welcoming committee that included Pence, Trump's adult children and their spouses.
Although the clan was enthusiastic and friendly, even then tension was evident within the larger Republican family.
Supporters of Cruz, gathered nearby for a rally celebrating his unsuccessful bid for the nomination, booed when Trump's plane came into view and chanted "2020! 2020!" — when, if all goes as Trump hopes, the Manhattan business mogul would be seeking a second White House term.
Of greater consequence, the convention was consumed for a third straight day by the controversy surrounding Melania Trump's Monday night speech, which pilfered lines from an address First Lady Michelle Obama gave at the 2008 Democratic convention.
On the streets outside the sports arena, the relative tranquility that has marked the week's protest scene was briefly punctured Wednesday afternoon when a group of demonstrators attempted to burn an American flag.
Eighteen demonstrators were arrested and two police officers suffered minor injuries.
In some good news, California GOP officials expressed optimism that a highly contagious virus that led to the quarantine of at least a dozen staff members was contained.
"We've had no new outbreaks for the last 24 hours, which makes me feel like all of our efforts to fight it … have worked," Cynthia Bryant, executive director of the California GOP, told the state's delegation at its breakfast meeting. "So knock on wood and say a prayer."
Times staff writers Cathleen Decker, David Lauter, James Queally and Seema Mehta contributed to this report.
For more political news and analysis follow me @markzbarabak on Twitter.
8:55 p.m.: This article was updated with Pence's address.
7:25 p.m.: This article was updated throughout.
4:45 p.m.: This article was updated with details on arrests and scheduled speakers.