The first round of the French elections is being held on Sunday. This year’s race is a challenge for pollsters, featuring four main candidates who are each polling at around 20 percent: the centrist Emmanuel Macron, the far-right Marine Le Pen, the far-right but not as far-right as Le Pen (and also corrupt, though we’re also talking about French politics) Francois Fillon, and France’s Bernie Sanders, Jean-Luc Mélenchon.

Until a late surge by Mélenchon, the race had been widely seen as the next great battle between the populist far-right and a centrist status quo. Le Pen has been repeatedly compared to Donald Trump—she hung out at Trump Tower during the transition—and some believe the race could be the harbinger of a “Frexit.” On Thursday, the election was rattled by a terror attack on Paris’s Champs Elysees that left one policeman dead.

ISIS quickly claimed responsibility for the attack, suggesting that it was intended to influence the election—radical terror groups, which are intent on driving a wedge between Muslims and Western society, believe that Le Pen’s National Front would help do this. Le Pen seized the initiative, saying the attack was a “symbol of [state] failure” and proof that France needs to fight back against Islamism. On Friday morning she got a boost from Trump, who made a similar, albeit subtler case:

Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election! — Donald J. Trump (@realDonaldTrump) April 21, 2017

Trump likes to try his hand at cable news punditry—in an alternate universe, he was given a Fox News show years ago and Greg Gutfeld is president—so this may just be Trump doing horse race analysis or parroting something he saw on TV. But it does crawl up to the edge of endorsing Le Pen—the implication seems to be that the terror attack will push the French to vote for Le Pen. (Trump’s own presidential campaign was boosted after the Paris terror attacks in 2015.)

The French elections have become a weird proxy war for American politicians—Barack Obama is backing Macron in a similarly subtle-but-not-too-subtle way. Still, it’s hard to think of a more irresponsible tweet from Trump, who is essentially signal-boosting the narrative that ISIS wants to promote.