Magazine publisher and businessman extraordinaire Steve Forbes has endorsed Gov. Rick Perry for president -- an endorsement that comes just as Perry prepares to unveil his proposal for a flat income tax rate, which Forbes says was the key to his decision.

"With firm leadership, which Rick Perry will provide -- which is why I'm endorsing him for president -- I think this will be a winning issue," Forbes told Fox News.

Forbes himself ran for president twice, and touted a flat tax plan as the centerpiece of his platform both times.

"People love the idea of radical simplicity of this horrific tax code," Forbes said.  "I think what Rick Perry's going to unveil on Tuesday is going to be very exciting -- very low rate, generous exemptions for adults and for children, making it worthwhile to invest in America again."

"Steve Forbes is a well known fiscal conservative, and provided strong support and advice throughout the process of drafting my economic and jobs plans," Perry said Monday in a statement. "I am honored to have Steve's endorsement of my candidacy for president."

The Texas governor is expected to unveil his own flat tax proposal in South Carolina on Tuesday, though the campaign has been tight-lipped on the exact details.  Forbes proposed a 17% flat tax during his presidential run, but says that Perry's proposed rate is likely to be lower than that.

"They have another number in mind, but it's a very low number, and his exemptions for adults and for kids is higher than what I proposed," Forbes said.  "I think people, as they learn more about it, are going to be excited about it."

Perry has recently struggled to maintain his standing in the presidential race, stumbling in his first few debates, and is likely hoping that Forbes' support and the proposed flat tax will revive enthusiasm for the campaign. 

"It's a capital creator, and job creator, which is why I'm backing Perry for president," Forbes said.  "He had a very good record in Texas, and I think this tops it off."