
One of the largest question marks as we approach the August 10th primary in Colorado is just how many votes will be cast. We can get some idea of the scale of this election by examining the last major contested primary in the state as well as data from states that have previously instituted mail-in ballot elections.
The last major contested statewide primary on the Republican side was the Coors-Schaffer race in 2004. The turnout numbers for this race can be used as a baseline for turnout in a non-mail-in ballot election between well-matched Republican opponents.
333,701 votes were cast in the 2004 Republican Senate primary. In August of 2004, there were 1,074,366 total registered Republicans. Secretary of State records also indicate that in August of 2004, approximately 73% of all registered voters in the state were also active voters. This means that out of around 784,000 active Republican voters in 2004 - 42% cast their ballots.
The latest numbers from the Secretary of State office show that there are 855,667 active registered Republicans. If turnout were to match 2004, we can expect 359,000 votes to be cast. However, this is the first mail-in ballot primary in Colorado and this will impact turnout.
The impact of all mail-in ballots on turnout is disputed among academic sources and tends to vary widely. However, some
recent research, as well as
trends from states that have put mail-in elections in place, indicates that a jump in turnout for a primary election for the first mail-in ballot election will be approximately five percent over the previous comparable election.
Using this model, it is likely that approximately 377,000 Republican votes will be cast in the 2010 primary. If Democrats experience comparable turnout, which early returns indicate they will, there will be
approximately 360,000 votes cast in the Democratic primary.
The mail-in ballot process in place this year should cause the primary turnout to rise above historical primary turnout. However, this will not be the massive increase in turnout that some campaigns are banking on. Instead, all things being equal, mail-in ballots seem to increase voter turnout incrementally each election cycle that they are used.