First time I've read of this. Can you suggest a good source for more info on how this worked since the Constitution specified selection by the state legislature? TIA...
Ask why the Lincoln-Douglas Debates were held across Illinois in 1858.
http://www.heritage.org/constitution/amendments/17/essays/178/popular-election-of-senators
...By 1912, Senators were already picked by direct election in twenty-nine of the forty-eight states...
...What happened is that the people in most of the states gradually turned to nonbinding primary elections to select their Senator; state legislators promised to vote for the Senator that the people had selected in this “advisory” election...
[Another, Leftist, source actually details some of the problems]:
...Between 1890 and 1900, no fewer than fourteen Senate seats remained vacant because of legislative deadlock. In Oregon in 1897, the State House was so badly split over the Senate vacancy that it never convened at all...