Barack Obama’s and Jimmy Carter’s Iaunch pad may have lost its magic

(CNN)The new CNN poll about where Democratic candidates stand in Iowa is out. And while former Vice President Joe Biden maintains his lead at 24%, it is narrower than in most recent polls. Some of his competitors, including Sen. Elizabeth Warren at 15% and Mayor Pete Buttigieg at 14%, seem to be gaining significant ground. This likely means that enthusiasm for Biden is not especially strong, particularly when compared to his competitors. And Carter and Obama aren’t unique. Among Democrats, seven party nominees have won in Iowa since 1976. Meanwhile, candidates who have ignored Iowa, such as former New York Mayor Rudy Giuliani in 2008, have sometimes suffered the consequences. But does Iowa really matter as much as it used …