It's a moment even the most experienced political pundits weren't expecting last night.
Ted Cruz took the stage the RNC and his speech stole the spotlight from Trump's VP pick Mike Pence when he didn't endorse Donald Trump.
"Vote your conscience for candidates up and down the ticket who you trust to defend our freedom and be faithful to the constitution," said Cruz.
Many delegates booed and security escorted Heidi Cruz away from the crowd
The senator explained his decision to the Texas delegation Thursday morning.
"I am not in the habit of supporting people who attack my wife and attack my father," said Cruz.
It's something few experts or voters saw coming.
"It was an interesting political move - I've never seen it," said USC student Charlie Heller.
"You don't see a lot of politicians going against their party," said Dennis Constanza.
But political expert Dan Schnur says the move likely more about strategy than political suicide.
"For all practical purposes, Ted Cruz announced his candidacy for President of the United States of the 2020 election last night. And for all practical purposes what he told the audience is "Donald Trump can't win and four years from now I'm going to run as the 'I told you' candidate," said Schnur.
It was a risk Trump was ready for.
"What Trump and his advisors decided was if we can't cancel his speech, we can completely undermine it," said Schnur.
While Cruz was still speaking, Trump walked onto the convention to distract the audience.
Schnur says Cruz's speech likely won't hurt Trump in the long run.
"If Donald Trump gives a well received speech tonight, everyone is going to forget everything that happened over the previous three days of the convention. If he struggles in the speech, and it backfires on him, that's what people will talk about Friday, over the weekend and next Monday," said Schnur.