Rep. Justin Amash of Michigan is now seeking the Libertarian Party’s nomination for president and Donald Trump is pretty excited about it.

I suspect Trump is right for once. While it’s true that the Libertarian Party was already likely to have a candidate on most if not all ballots in the country, Amash has good name recognition and more political skills than the typical Libertarian nominee. He will boost the party’s performance.

The next question is obviously whether he’ll pull more votes from Trump or from Biden. In general, the Libertarians are right-leaning just as the Greens are generally left-leaning. This would ordinarily mean that some Republicans would opt for the Libertarian because their ideology is more libertarian than conservative. It’s the same assumption Trump is making with respect to 2016 Green Party candidate Jill Stein–that she helped him by attracting a portion of the left, thereby denying Hillary Clinton some votes.

However, the 2020 election is shaping up to be a ‘yes’ or ‘no’ vote on Trump rather than an expression of ideological preference. The more options people have for saying ‘no,’ the more diluted the ‘no’ vote will be. The simplest way of demonstrating this is to imagine ten voters, five of whom support Trump and five of whom do not. If one of those Trump opponents votes for Amash, then Trump wins 5-4-1.

This is the more likely scenario than the one where five liberals and five conservatives vote, and one conservative opts for Amash, giving Biden the victory. The best situation is the one in which nearly all anti-Trump votes go to Biden. Justin Amash makes that less likely.

Now, this could be somewhat offset by a certain kind of voter. This voter is basically unwilling to cast a ballot for a Democrat under any circumstances, and also unwilling to stay at home or leave the ballot line blank. In a choice between Trump and Biden, they’d choose Trump even though they’re very unhappy with him. Amash gives them a chance to register their displeasure without supporting a party they loath. These people do exist, and Amash will win their votes. The problem is that I believe there are probably just as many people on the far left who would use Amash’s ballot line for the same purpose.

In one sense, Biden can benefit from having another voice amplifying his criticisms of Trump, but Amash will also be looking to attract people on the left who are critical of Biden’s record. He will have some success in this, especially because many of the strongest criticisms of Biden align with libertarian philosophy–think drug war and foreign policy. He also has more credibility with the left than the average Libertarian candidate because he quit the Republican Party and voted to impeach the president.

It’s hard to say with certainty, but I think it’s a good bet that Amash will pull in more potential Biden voters than Trump voters. I also think this is largely out of his control. He can have some influence through what he chooses to emphasize, but he’ll always be more of a receptacle for protest than a true vote-getter.  The protest vote is anti-Trump, so almost by definition he’ll be diluting it.