Party raiding
A notable example of attempted party raiding was Operation Chaos in the Democratic primary in 2008 when Rush Limbaugh encouraged Republicans to vote for Hillary Clinton in an effort to weaken Barack Obama politically . 
<triplet> Democratic primary <subj> 2008 <obj> point in time <subj> Hillary Clinton <obj> candidate <subj> Barack Obama <obj> candidate <triplet> Rush Limbaugh <subj> Republicans <obj> member of political party