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Ted Cruz went on a blistering ramble against Donald Trump on Tuesday, delivering a list of stinging personal attacks that included calling the GOP frontrunner a “serial philanderer,” “pathological liar” and a “narcissist.”

The attacks came on the day of the Indiana primary and hours after Trump repeated a tabloid report tying Cruz’s father, Rafael Cruz, to the assassination of President John F. Kennedy.

“This man is a pathological liar. He doesn't know the difference between truth and lies. He lies practically every word that comes out of his mouth,” Cruz told reporters in Evansville, Indiana.

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The Hoosier State primary is crucial for Cruz’s goal of preventing Trump from gaining enough delegates to secure the GOP presiential nomination. Most polls show Trump with a lead in the state, and Cruz’s attacks against his rival on Tuesday went into his personal life in a way Trump’s opponents have largely avoided until now.

“Donald Trump is a serial philanderer and he boasts about it,” Cruz said. “This is not a secret, he is proud of being a serial philanderer."

The Texas senator also echoed an attack used by Hillary Clinton, saying Trump is afraid of strong women and is a “bully” to females.

That was an impressive meltdown... Desperate but impressive. Reminded me of my 3 year old coming off a sugar high. https://t.co/3lqwHIRWo6 — Donald Trump Jr. (@DonaldJTrumpJr) May 3, 2016

“If anyone has seen the movie ‘Back to the Future II’, the screenwriter says that he based the character Biff Tannen on Donald Trump, the caricature of a braggadocious, arrogant buffoon...We are looking, potentially, at the Biff Tannen presidency,” Cruz said.

Trump responded in a statement: "It is no surprise he has resorted to his usual tactics of over-the-top rhetoric that nobody believes. Over the last week, I have watched Lyin’ Ted become more and more unhinged...Today’s ridiculous outburst only proves what I have been saying for a long time, that Ted Cruz does not have the temperament to be President of the United States."

The senator has avoided directly answering whether he would support Trump as the Republican presidential nominee. But the increasingly personal battle between the two candidates who earlier in the campaign had an informal alliance brings into question how the party will unite once a nominee is selected.

And though Cruz has vowed to continue his campaign as long a viable path to the nomination exists, he talked about the impact of Tuesday’s results in no uncertain terms.

“If Indiana does not act, this country could well plunge into the abyss,” Cruz said.