A new French book that decries income inequality has become such the rage among the U.S. left that it is sparking debate on a smoldering political issue: That Hillary Clinton isn't liberal enough to win the Democratic nomination in 2016.

Thomas Piketty's “Capital in the Twenty-First Century” uses a mountain of historical data to show that income inequality, a subject President Obama has seized on, will grow without government intervention. One idea is to devote up to three-quarters of income to taxes.

Progressives, many of whom are eyeing Massachusetts Sen. Elizabeth Warren or even Vermont Sen. Bernie Sanders leading up to 2016, see the issue as a winner in the election and aren't satisfied with Clinton's more moderate approach.

Scott W. Rasmussen, the former pollster, took that one step further in his column Thursday, suggesting that if Democrats continue to seek more government intervention, Clinton won't win the nomination.

“It is,” he wrote, “the latest reason to believe that Hillary Clinton will not be the Democratic presidential nominee in 2016.”

Rasmussen writes that many Democrats don’t believe that Obama has been liberal enough, and he’s left of Clinton. “People with such attitudes see former Secretary of State Hillary Clinton as even more ‘conservative’ than the ‘centrist’ Obama.”

Several pundits and media outlets have suggested that Warren could be poised to seize the new Democratic mood. “Why Elizabeth Warren is perfectly positioned for 2016 (if she wanted to run),” was a headline on the Washington Post's website Thursday.

Rasmussen might agree. He concludes his column this way:

“As a result, the public embrace of Piketty's book by leading liberal voices creates one more reason to believe that Clinton will not be the party's presidential nominee in 2016. The party is leaving her behind as it becomes more liberal. Additionally, the views expressed in Piketty's book are a repudiation of former President Bill Clinton's tenure in the White House. He rescued the Democrats from similar elitist attitudes a generation ago by adopting a more centrist approach.

“If the party wants to revert to its pre-Clinton ways, Hillary Clinton will not be the messenger.”

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.