The two leading contenders for the GOP presidential nomination were a study in contrasting style in dueling speeches at an annual Tea Party convention in Myrtle Beach, S.C., on Saturday.

Sen. Ted Cruz's tone and delivery mirrored that of a Sunday sermon. Donald Trump's seemed more geared toward a Saturday night bar crowd. (He opened his remarks by thanking the dozen or so Myrtle Beach motorcycle bikers who stood outside cheering for him.)

In his speech, Cruz made no mention of Trump. But the Texas senator wasn't ignoring his rival: Cruz mocked Trump's Twitter account in a conversation with reporters earlier in the day. "I think in terms of a commander-in-chief, we ought to have someone who isn't springing out of bed to tweet in a frantic response to the latest polls," Cruz said.

Trump, who appeared before the same audience two hours later, took the freshman Texas senator head on, targeting Cruz's failure to report to the Federal Election Commission nearly $1 million of loans from Goldman Sachs and Citigroup to fund his successful 2012 Senate campaign.

"You give a campaign contribution to Ted Cruz, and you get whatever the hell you want," the billionaire businessman said. Cruz supporters immediately began booing him. "Excuse me, excuse me," Trump interrupted back. "Say whatever you want — he didn't report his bank loans."

"Disgusting, rude and obnoxious," was how Cruz supporter Betty Wood, from suburban Atlanta, reacted after Trump's speech. Trump backer Aileen Milton, from Florida, disagreed. "Cruz deserved it — he's a politician like all the rest of 'em," she said. Despite their differing reactions to the two candidates, Wood and Milton conceded that their second choice would be Trump or Cruz, respectively.

Trump leads in most Republican national polls. But he is locked in a battle for first place with Cruz in Iowa, an evangelical stronghold where caucusgoers will kick off the 2016 presidential voting on Feb. 1.

Trump is also leading the GOP field in New Hampshire, where independents and centrist Republicans are key constituencies. Cruz's campaign is hoping that momentum in Iowa will help him in South Carolina, where polls show Trump with a big lead ahead of the Feb. 20 Republican primary. It's a state where small-government fiscal conservatives have at least as much clout as social conservatives.

'A nasty guy'

On Sunday, the feud between the two front-runners escalated.

Trump called Cruz "a nasty guy. Nobody likes him. Nobody in Congress likes him. Nobody likes him anywhere once they get to know him," Trump said in an interview on ABC's "This Week" that aired Sunday. "He's got an edge that's not good. You can't make deals with people like that, and it's not a good thing. It's not a good thing for the country."

"Very nasty guy," Trump said.

Cruz's campaign has gone on the offensive, tweeting and e-mailing a video of Trump on "Meet the Press" in 1999, during which Trump called himself "very pro-choice" and admitted that he viewed gay rights differently from a voter in the heartland.

"I lived in New York City and Manhattan my whole life, so my views are a little bit different from if I lived in Iowa," Trump said then.

Cruz spokesman Rick Tyler said that the campaign will highlight contrasts between Cruz and Trump to illustrate that voters can be confident that Cruz has "guiding principles to make critical decisions as president and commander in chief."

Trump "has policy proposals that just don't seem serious," Tyler said.

When asked why Cruz decided to go after Trump last week, Tyler said, "We have three weeks to go" until the Iowa caucuses.

"Donald Trump started the fight with us, we're glad to finish it," Tyler said.