Donald Trump slammed potential 2016 Republican presidential candidates Mitt Romney and Jeb Bush, telling a sold-out crowd Saturday at the Iowa Freedom Summit there is “no way” they would win.

“The last thing we need is another Bush,” the real estate mogul and sometimes-conservative pundit told the crowd, which erupted in applause. “He’s very, very weak on immigration. His brother gave us Obama – because Abraham Lincoln coming back from the dead could not have beaten Obama.”

He added, “And Mitt? No.”

The Des Moines summit is packed with potential 2016 GOP candidates, who are set to speak throughout the day. Romney and Bush, though, did not attend, making them an even bigger target for event organizers and speakers who deem them too moderate, particularly for the first-in-the-nation caucus state.

Trump, in his signature style, laid out a laundry list of reasons why conservatives should not vote for Romney or Bush and said if he were president, the first thing he’d do is build a fence to keep out illegal immigrants.

“I’m Trump. I build things,” he said, toying with the crowd that he might run for president in 2016. 

The latest headlines on the 2016 elections from the biggest name in politics. See Latest Coverage →

Trump told the crowd his international business associates laugh at America’s leadership and said he’d restore respect if elected.

“I’m looking at it very seriously … I want to make this country great again,” Trump said. “I am seriously thinking of running for president.”