Three senators seen as top contenders for the 2016 Republican ticket on Sunday flocked to a "conversation" hosted by the Koch brothers' Freedom Partners that offered "a preview of the GOP primary debates that begin in August," the Washington Examiner reported.

Ted Cruz of Texas, Rand Paul of Kentucky and Marco Rubio of Florida took part in the event hosted by the umbrella operation of the political groups sponsored by the billionaire siblings. The Palm Springs, California forum, moderated by ABC News White House correspondent Jonathan Karl, attracted conservative activists and donors from around the country.

The three hopefuls agreed that President Obama deserves no credit for the economic recovery, Politico noted, and they pointed to what they view as Hillary Clinton's close ties to the incumbent. Although she has yet to officially announce a White House run, the former New York senator and secretary of state is seen as the clear Democratic front-runner in the 2016 race.

"I have to say I chuckle every time I hear Barack Obama or Hillary Clinton talk about income inequality," Cruz said, "because it's increased dramatically under their policies."

But the three senators disagreed -- at times sharply -- when it came to foreign policy, according to the Los Angeles Times. President Obama's recent attempts to ease tensions with Cuba, for example, proved a particularly contentious point.

"We've tried an embargo for 50 years; it hasn't worked," said Paul, adding that open trade with the United States "actually would benefit" the island nation's oppressed citizens.

"There isn't a single contemporary example of that happening," Rubio shot back. The Florida senator, the son of Cuban parents who immigrated to the United States in 1956, received support from Cruz, who called Obama's decision "a terrible mistake."

"This will result in billions of dollars more for the Castro regime," Cruz insisted.

None of the three presumed presidential contenders, meanwhile, took issue with the role their hosts play in the political process. Rubio "replied mockingly" when asked if exceedingly wealthy donors wielded too much influence, the Los Angeles Times said.

"As opposed to Hollywood or the mainstream media, you mean, or other multibillion-dollar entities that try to influence American politics every day?" the Floridian asked.

The Koch brothers' network aimed to spend $290 million on advocacy ahead of the 2014 mid-term elections alone, and the siblings are "frequently criticized by Democrats as being secretive bankrollers of Republican causes and campaigns," Newsweek recalled.