Time magazine (October 25) carries the article titled “The Populist Egghead” with a caption:
“Sen. Cruz isn't being mocked for low wattage the way Palin and Reagan had been. He's being singled out for a lack of common sense born of his rarefied résumé.”
The sentence follows:
The populist claims to possess the horse sense of the electorate and has no need for fancy schools, with their eating clubs, trays of sherry, and debating societies. That was Sarah Palin's (and Reagan’s) posture. http://www.slate.com/articles/news_and_politics/politics/2013/10/ted_cruz_is_a_populist_egghead_the_texas_senator_has_elite_credentials_but.html
I understand ‘low wattage’ is a figurative adaptation of electrical power, but what does it exactly mean in the above quote? Is it a common expression? Were both Sara Palin and Reagan really ‘low wattage’?