The Des Moines Register's Tom Beaumont reports that Democrats and Republicans in Iowa have agreed to hold the state's 2010 caucuses on a Saturday, breaking with a long-term tradition where caucuses were held on Tuesday evenings. 2010 isn't a presidential year, you say... Well, yes: for Iowans, the caucuses aren't just a feature of presidential races. They're crucial parts of state legislative elections. The basic theory behind the shift to Saturday is that more people will participate -- more people of more types. In some ways, given the mammoth turnout operation that Barack Obama's Iowa team used to diversify the 2008 precinct caucuses, maybe a move to Saturday wasn't necessary. But Obama's not going to be able to drive turnout like that again. The institutional resistence to change has been weakened by his success -- and by dedicated supporters of Hillary Clinton's, who believe that her voter type -- white, working class -- just wouldn't turn out after a long day of work on Tuesday night, giving professional and college-town liberals an advantage. As Beaumont writes, 2010 will be a "great experiment."