Republican Ted Cruz launched a blistering attack on rival Donald Trump as voters cast ballots in Indiana on Tuesday, calling him "amoral" and likening him to a fictitious character he described as "a braggadocios, arrogant buffoon."
The attack came in response to Trump repeating unsubstantiated claims that Cruz's father, Rafael Cruz, was acquainted with John F. Kennedy's assassin, Lee Harvey Oswald.
"The whole thing is ridiculous," Trump said on Fox & Friends Tuesday. "Right prior to his being shot, and nobody brings it up. They don't even talk about that."
A recent National Enquirer report claimed that the elder Cruz appeared in a 1963 photo of Oswald as he handed out leaflets for the Fair Play for Cuba Committee.
The Cruz campaign has denied the accusations and Cruz called his dad "my hero."
Speaking to reporters in Evansville, Indiana, Cruz warned that the country could "plunge into the abyss" if Trump is elected president.
"We are not a proud, boastful, self-centered, mean spirited, hateful, bullying nation," Cruz said, with his wife Heidi and running mate Carly Fiorina by his side.
Cruz faces a high-stakes test of his presidential campaign in Tuesday's primary, one of the last opportunities for the Texas senator to halt Trump's stunning march toward the GOP nomination.
"I am in for the distance, as long as we have a viable path to victory," Cruz told reporters on Monday.
Cruz on Tuesday called Trump "a pathological liar" who "doesn't know the difference between truth and lies."
"Donald Trump is a serial philanderer and he boasts about it," Cruz went on to say. "This is not a secret, he is proud of being a serial philanderer...Describes his battles with venereal diseases as his own personal Vietnam."
Trump responded to Cruz's attack in a statement, saying: "Ted Cruz is a desperate candidate trying to save his failing campaign. 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 as he is unable to react under the pressure and stress of losing, in all cases by landslides, the last six primary elections --- in fact, coming in last place in all but one of them. 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."
Cruz has spent the past week camped out in Indiana, securing the support of the state's governor and announcing retired technology executive Carly Fiorina as his running mate. Yet his aides were pessimistic heading into Tuesday's voting and were prepared for Cruz to fall short, though the senator vowed to stay in the race, regardless of the results.
"I am in for the distance, as long as we have a viable path to victory," Cruz told reporters on Monday during a campaign stop.
But on Tuesday, he was a no-show at a morning campaign stop outside of Indianapolis. Cruz was supposed to campaign alongside his wife Heidi and Fiorina at a pancake restaurant, but 30 minutes before the scheduled start of the event, Cruz's campaign said the senator would not be there.
Cruz spokeswoman Catherine Frazier said they made a mistake in saying originally that he would be there. Cruz is slated to make a campaign stop in the southern Indiana city of Evansville later Tuesday morning, then he will take the afternoon off before his primary night gathering in Indianapolis.
Fiorina and Heidi Cruz did show up to shake hands and talk with diners.
Trump devoted more time to campaigning in Indiana than he has to most other states, underscoring his eagerness to put his Republican rival away and shift his attention toward Democratic front-runner Hillary Clinton.
While Trump cannot clinch the nomination with a big win in Indiana, his path would get easier and he would have more room for error in the campaign's final contests.
"Indiana is very important, because if I win that's the end of it. It would be over," Trump said during a lunch stop Monday in Indianapolis.
Republican leaders spent months dismissing Trump as little more than an entertainer who would fade once voting started. But Republican primary voters have stuck with the billionaire businessman, handing him victories in every region of the country, including a string of six straight wins on the East Coast.
Clinton and Vermont Sen. Bernie Sanders also faced off in Indiana's Democratic primary on Tuesday, though the stakes were lower than in the Republican race. Clinton holds a commanding lead over Sanders — she's secured 91 percent of the delegates she needs to win the nomination. That means she can still win the nomination even if she loses every remaining contest.
Sanders has conceded that he faces a difficult path to overtake Clinton, one that hinges on convincing superdelegates to back him over the former secretary of state. Superdelegates are Democratic Party insiders who can support the candidate of their choice, regardless of how their states vote. And they favor Clinton by a nearly 18-1 margin.
Neither Clinton nor Sanders planned to spend Tuesday in Indiana. Sanders was making stops in Kentucky, which holds a primary in mid-May, while Clinton moved on to Ohio, a key general election battleground.
Clinton's team has started deploying staff to states that will be crucial in November and is also raising money for the fall campaign. Even as Trump hires more staff to round out his slim team, he already lags far behind Clinton in general election preparations.
A showdown between Clinton and Trump would pit one of Democrats' most popular and highly-regarded figures against a first-time political candidate who is deeply divisive within his own party. Cruz and other Republicans have argued that Trump would be roundly defeated in the general election, denying their party the White House for a third straight term.
But Trump is the only Republican left in the race who can secure the 1,237 delegates needed for the nomination through regular primary voting. Cruz — as well as Ohio Gov. John Kasich, who trails significantly in the delegate count — must try to block Trump in Indiana and the handful of other remaining states to push the race toward a contested convention.
In an abrupt strategy shift, Cruz and Kasich announced an alliance of sorts in Indiana. The Ohio governor agreed to stop spending money in Indiana to give Cruz a chance to compete head-to-head with Trump. Cruz has pledged to do the same for Kasich in Oregon and New Mexico, which vote in the coming weeks.
But that strategy, which appeared to unravel even as it was announced, may have backfired. A recent NBC News/Wall Street Journal/Marist poll found that nearly 6 in 10 Indiana primary voters disapproved of the Cruz-Kasich alliance.
"After they made the alliance, their numbers tanked," Trump said Monday. "That's what happens when politicians make deals."