Forbes, the chairman and editor-in-chief of Forbes Media, said former Florida Gov. Jeb Bush had the right strategy while he was in the race, but the wrong execution.
"[Bush] talked about 4 percent GDP growth. I understood what he was saying, but [to] most people it sounds like a hair formula," Forbes said. "Bush was too abstract," he continued, arguing Bush failed to connect the dots and convey how his ideas would change the country.
Forbes said candidate and president Ronald Reagan, on the other hand, was great at communicating his vision. "Reagan had a wonderful way of translating these things in a way people would actually understand how they might improve their lives and the country."
Reagan was a larger-than-life figure, Forbes added. "But Reagan always made sure it was beyond him. It was not just the personality. He had something he stood for."
The current candidates vying to stay alive in the Trump-dominated race should use some of Reagan's tricks of the trade, he said. "You just can't say, 'I don't like Donald Trump; I don't like what he does.' You have to have an alternative. And that's why, I think, you're seeing people rally around Cruz."
Over the weekend, Trump was forced to address the violent encounters at his campaign events.
The billionaire businessman criticized the protesters who forced him to cancel an event in Chicago on Friday. On NBC's "Meet the Press" on Sunday, Trump said: "I do not accept responsibility. I do not condone violence in any shape."
On the campaign trail, Cruz won the most delegates awarded in the Wyoming Republican conventions Saturday, while Rubio narrowly beat Kasich in Washington, D.C.
The Florida primary was seen as make or break for Rubio, who trails in his home state to Trump by 18.7 percentage points in the latest polls aggregated by RealClear Politics.
If Trump were to get to this summer's GOP convention with a plurality of delegates but not enough to claim the nomination outright, Forbes said it would be "chaotic."
"If you have a contested convention, each delegate is going to want his or her 15 minutes of fame," he argued. "There is no bosses."
"The dirty little secret today is there is no establishment, certainly not on the Republican side," Forbes said. "You have officials from the past, [and] party officials today being paid by donors. They have no clout."