The former presidential primary opponent that Mr Donald Trump always referred to as Lyin' Ted during his campaign speeches - Texas Senator Ted Cruz - caused what's possibly the biggest stir of the Republican National Convention thus far when he told delegates on Wednesday (July 20) to "vote your conscience" instead of endorsing the New York billionaire.
Mr Cruz came in second behind Mr Trump during the primary campaign race for the Republican nomination earlier this year. While on the campaign trail, Mr Cruz, like most other candidates in the race, faced withering insults and criticism from Mr Trump.
At first it appeared he might surprise a convention still trying to rally Republicans round the candidate they have nominated for president of the US, and delegates appeared ready to give him and his speech a rousing ovation.
"Please, don't stay home in November," Mr Cruz said to applause and chants for him to endorse Mr Trump. The cheering, however, quickly turned to boos and chants of "We want Trump".
"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, vote for candidates up and down the ticket who you trust to defend our freedom and to be faithful to the Constitution," said Mr Cruz.
Earlier in the convention, anti-Trump forces led by delegates supporting Mr Cruz's unsuccessful bid had tried to make rule changes that would have allowed delegates to vote their conscience.
Apparently realising the snub, Mr Trump's handlers rushed him into the convention hall soon after, as Mr Cruz was winding up his speech. He applauded but then waved to the packed Quicken Loans Arena in an apparent attempt to distract them from the Texas senator.
Indeed, Mr Cruz only mentioned Mr Trump once at the beginning of his speech to congratulate him on winning the nomination.
CNN later reported that "the anger is boiling over" and that when Mr Cruz walked in to a donor suite after the speech, "people were so angry at him that they were calling him a disgrace to his face". It also reported a source as saying that a "state party chair was yelling at him (Mr Cruz) so angrily that he had to be restrained".
The Texas senator's wife was also nearly attacked. A reporter for the Richmond Times-Dispatch posted a video showing security officers escorting Mrs Heidi Cruz out of the Quicken Loans Arena as hecklers screamed insults at her.
During the campaign for the party’s nomination, Mr Trump rarely mentioned Mr Cruz without calling him "Lyin' Ted". He also took shots at the looks of Mr Cruz’s wife and implied that the Texan’s father was somehow involved with the assassination of President John F. Kennedy in Dallas in 1963
The latest incident at a Republican National Convention that was supposed to have showcased Mr Trump added to a series of gaffs and miscues and threatened to overshadow the speech of the night by his chosen vice presidential running mate, Governor Mike Pence of Indiana, a state neighbouring Ohio.
In fact, Ohio's Republican own governor, Ted Kasich, has been conspicuous by his absence from his party's convention being held right in his own state.
Other major party figures who are not at the convention because of their dislike for Mr Trump include former President George W Bush, and both the party's 2012 nominee Mitt Romney, and 2008 nominee Senator John McCain of Arizona.