Texas Sen. Ted Cruz ratcheted up the religious overtones in his bid for an upset victory in Tuesday’s Indiana Republican presidential primary, suggesting in a radio interview that Donald Trump has “contempt” for Christians and views prayer as a “sign of weakness.”

He then fired off a fusillade of put-downs while speaking to reporters at a stop in Evansville, Ind., calling Trump “utterly amoral” and a “pathological liar.”

Just hours earlier, Trump blasted his rival’s father, Rafael Cruz, for making a similar religious appeal and waing against electing a “wicked” candidate. Trump, speaking with Fox News, called the remarks “disgraceful” and “horrible” – and insisted he’s “wiing the evangelical vote.”

The sparring Tuesday marked the final leg of a barbed primary battle, as voting got well under way in a state that could help decide whether Trump can clinch the GOP nomination outright, or must wade into an open convention battle in July.

The primary widely is seen as a make-or-break moment for Cruz, who trails in most polls but has campaigned aggressively in pursuit of an upset.

To that end, he and his father both have appealed to the state’s Christian community in a bid to boost tuout.

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Speaking Tuesday on Gle Beck’s radio show, Ted Cruz claimed Trump “views prayer as a sign of weakness.”

He continued: “And the people of Indiana can choose. Do you want that in the Oval Office? You think Obama has been bad with the contempt he has heaped on Christians? You ain’t seen nothing yet compared to Donald J. Trump.”

After Cruz went on to call Trump "amoral," Trump issued a statement calling Cruz a “desperate candidate” and saying, “It is no surprise he has resorted to his usual tactics of over-the-top rhetoric that nobody believes."

Trump, meanwhile, has aggressively courted Indiana voters, telling them that if they deliver a victory to him on Tuesday the race is “over” and he can start concentrating on Democratic front-ruer Hillary Clinton.

Clinton, too, is looking to Indiana’s primary to sideline underdog rival Beie Sanders, who despite losing most recent primary contests has vowed to keep fighting to the convention. Clinton and Trump both have started to tu their attacks on each other, anticipating a general election match-up, but are still dealing with their respective primary rivals.

Trump even found himself battling with Cruz’s father on Tuesday.

Speaking with the head of the American Family Association of Indiana, the elder Cruz, a pastor, had waed of the “wicked electing the wicked” and urged fellow Christians to come out to vote.

“I implore, I exhort every member of the body of Christ to vote according to the word of God, and vote for the candidate that stands on the word of God and on the Constitution of the United States of America," Cruz said. "And I am convinced that man is my son, Ted Cruz. The alteative could be the destruction of America."

Trump fired back on Fox News Tuesday moing.

“I think it’s a disgrace that he’s allowed to do it. I think it’s a disgrace that he’s allowed to say it,” Trump said.

The back-and-forth came after Cruz earlier told Hoosier voters that Americans are “praying” for them. He waed against giving “in to evil.”

Asked Monday what he meant by that, the Texas senator said, “We are not a bitter, angry, petty, bigoted people. That is not America.”

According to the Pew Research Center, 72 percent of Indiana residents identify as Christian.

Republicans are competing for 57 delegates in the Indiana primary; Democrats are competing for 83 delegates.

Fox News’ Dan Gallo contributed to this report.