litmus test
litmus test
1.
(Chemistry) A test to determine acidity or alkalinity, using litmus as an inddicator.
2.
(Politics) A test for a single factor, which has only two outcomes, positive or negative;
(Politics) the question of whether a candidate for office is for or against a particular position on an issue; -- used, for example by voters concerned predominantly with a single issue, to decide whether to vote for or against a candidate; as, many voters take a candidate's position on abortion as their litmus test. [Figurative]