Democratic presidential candidate Martin O'Malley slammed Sen. Ted Cruz (R-Texas) Wednesday, calling him the most "unqualified" and "outrageous" candidate in the 2016 field. O'Malley, along with Hillary Clinton and Bernie Sanders, spoke at the "Battle Born/Battleground" caucus dinner, hosted by the Nevada Democratic Party and Sen. Harry Reid.

"I'd like to say that Donald Trump is the most outrageous and unqualified person ever to run for president," said O'Malley at a rally in Nevada, reported NBC News. "But, really, that's not fair to Ted Cruz."

The former Maryland governor particularly hit Cruz on his solution to mass shootings. "Cruz actually says that the answer to gun violence is more guns," he said, according to the New York Times. "Senator, the answer to cancer is not more cancer, the answer to poverty is not more poverty, and the answer to gun violence is not more guns."

In recent weeks, the once cordial Republican rivals have sniped back-and-forth beginning with released audio from a private fund-raising event in which Cruz questioned Trump's "judgement," reported the New York Times. In turn, Trump has called into question Cruz's evangelical Christian roots and his eligibility for being president because of his Canadian birthplace.

"Republicans are going to have to ask themselves the question: 'Do we want a candidate who could be tied up in court for two years?' That'd be a big problem," Trump told the Washington Post in an article published Tuesday, referring to the Texas senator. "It'd be a very precarious one for Republicans because he'd be running and the courts may take a long time to make a decision. You don't want to be running and have that kind of thing over your head."

"I'd hate to see something like that get in his way," he added. "But a lot of people are talking about it and I know that even some states are looking at it very strongly, the fact that he was born in Canada and he has had a double passport."

In current national polling, Cruz is the only Republican presidential candidate who is closest to Trump, the party's front-runner. According to RealClear Politics national averages, Trump leads the field with 35 percent while Cruz has 20 percent.