Complex sentence: In 2014 he received a narrow plurality in his race for re-election, but did not attain the 50% threshold mandated by the Vermont Constitution, therefore requiring the Vermont General Assembly to select the winner.
Split into simpler sentences: In 2014 he received a narrow plurality in his race for re-election, but did not attain the 50% threshold mandated by the Vermont Constitution. In such cases the Vermont General Assembly to select the winner.