Serving the Flathead Valley & Montana since 2006. A reality based independent journal of observation & analysis. © James Conner.
The short answers: Yes, in some GOP primaries, and No in most cases. In Ravalli County, Democratic crossovers may have helped defeat tea partier Scott Boulanger in Senate District 43, and may have helped defeat some tea party affiliated candidates for the county commission. But I have not performed a statistical analysis of these contests.
In the Flathead, there’s a strong statistical case that relatively large numbers of Democrats voted in the Republican primaries in House Districts 7 and 11, and in Senate District 4. Crossover voting probably didn’t matter in HD-7 and SD-4, but it may have helped Dr. Albert Olszewski defeat hard right Mike Hebert in HD-11.
There was a strong case for Democratic crossover voting in the Kalispell and Somers-Lakeside legislative districts, but also a case for Democrats voting in their own primaries to ensure the defeat of U.S. House candidate John Driscoll, who was trying to reprise his 2008 takedown of Jim Hunt (Driscoll won that primary, then endorsed Republican Denny Rehberg that fall), and to make a difference in the Democratic primary for U.S. Senator.
In the Flathead, Bill Baum wrote opeds and letters-to-the-editor urging Democrats to crossover to support Cal Scott for county commissioner. It was clear pretty much from the gitgo that Scott would lose the primary in a landslide, so I doubt that Baum generated many crossovers.
Crossover voting seldom makes a critical difference unless a political party endorses it, and puts some money and political muscle behind it. That didn’t happen in Montana, although a key Democratic ally, the MEA-MFT union, did urge its members to consider voting for the least conservative Republican candidates in targeted districts.