Father Frank Pavone, the head of Priests for Life, is one of the anti-abortion leaders who have reluctantly come around to Donald Trump now that he is the presumptive GOP presidential nominee, saying last week that for abortion rights opponents, the choice between Trump and a Democrat is a choice “between doubt and certainty.”

Pavone explained his thinking more in an interview Tuesday on Ave Maria Radio, saying that he reminds people who are having doubts about voting for Trump about the importance of Supreme Court nominations and presents them with an utterly depressing analogy:

Here’s the analogy I’ve been using for folks to consider: It’s like being on a runaway train. Let’s presume, it’s an odd situation, but let’s presume that you’re at the controls of a runaway train. And the train cannot be stopped and you know that at the end of the track it’s going to do damage, so you can’t stop the train. But supposed the only thing you could do is to switch the track that the train is on so that at the end of Track A it’s going to kill 10 people and at the end of Track B it’s going to kill 100 people. Now, you don’t want to kill anybody. Nobody wants to kill anybody. But you can’t stop the train. So, what are you going to do? Are you going to say, ‘Oh, I’m not going to do anything’? Or are you going to do your best to switch it to the track where it’s going to do less damage. Now, some people say, ‘I don’t want to kill 10 people and I don’t want to kill 100 people, so I’m not going to do anything.’ Yeah, but if the train is on the track, then, to do the more damage, don’t you share responsibility for not doing something to try to minimize the damage? This is not the choice between the lesser of two evils: We don’t choose evil at all. It’s a choice to limit evil. And the choice to limit evil is a good.

He added that according to the catechism, voting is “morally obligatory.”