Republicans have taking a big lead in early voting in Colorado, and the lead has only gotten bigger. A report from the Secretary of State this morning showed that over 112,000 more Republicans than Democrats had cast their ballots as the state conducts its first major mail-in election. Voters can also drop off ballots at polling stations and register through Election Day. Republicans usually lead in early returns in Colorado but rarely by such hefty margins. Democrats and some observers expect that lead to shrink by Election Day. But more than half the ballots are in and the filing suggests how difficult it might be for Democrats such as Senator Mark Udall to survive a year in which Republicans are highly motivated.