In an interview with CNN's Erin Burnett, Gov. Bill Richardson admitted he's "a little concerned" about President Obama's slumping popularity among Hispanic voters. But compared to potential Republican challengers, Richardson says, he expects the president will fare strongly, saying he's "on the right side" of the issues that matter most to Hispanic voters, such as immigration.

CNN's Erin Burnett crunched the numbers on Texas governor Rick Perry's flat tax proposal, and says in reality, the plan's more "lumpy" than flat. Still, it holds promise to some–especially in the form of its one-page "postcard" tax form. Can the plan work? And where would the budget cuts come from? Erin talks to David Malpass, an economic adviser to Perry.

On CNN's Situation Room, Erin Burnett joined Wolf Blitzer to talk about the flat tax. Republican presidential candidate Rick Perry has become the latest to advance a flat tax proposal–but will it fly? And what would it mean for the country?

Erin discusses the flat tax concept with Wolf, and she'll dig deep into the tax concept on OutFront tonight at 7pET.