By Catalina Camia, USA TODAY
Rick Santorum may have scored a political hat trick Tuesday night, but voter turnout was down in Colorado, Minnesota and Missouri. That continues a trend that began in Florida and occurred again in Nevada.
Political experts say the downward slide in turnout could pose challenges for Mitt Romney, who has had trouble consistently exciting the GOP base.
"Republicans are upset with their field," Steven Schier, a political scientist at Carleton College in Minnesota, told USA TODAY. "If you look at national polls, a large percentage would like other candidates. It's too late for that and many are stuck with unappealing choices. That produces low turnout and that's a real threat to Romney."
In Colorado, where Romney campaigned heavily, turnout was down about 7% from 2008, according to data compiled by MSNBC's First Read. In Minnesota, turnout was down by 24%. And in Missouri, which was a "beauty contest" primary with no impact on delegate allocation, voting was down 57%.
Michael McDonald, a professor at George Mason University who tracks election turnout, said Romney has shown he can score victories in suburban areas where there are more moderates.
But candidates such as Santorum and Newt Gingrich have been able to excite a more passionate electorate. In Florida, for example, turnout was up in the more rural counties where Gingrich beat Romney.
McDonald said Romney's appeal among moderates could change if he becomes the GOP nominee against President Obama, who will compete with him for some of the same voters.
"In some ways, it is good news for Romney that Santorum did so well because it continues to fracture that conservative base," he told USA TODAY. "Without an opponent who can rally all the conservatives, he can still win contests but he cannot win if there's only one conservative alternative."
