Admiral Markets, a European-regulated forex broker, announced it is temporarily hiking the margin requirements on all instruments ahead of the upcoming presidential elections in France on April 23 and the eventual market volatility.
Additionally, the broker could enable Close Only mode for any instruments on separate short notice within the same periods.
Frankly, considering how important these elections are for the entire European Union I doubt they'll be the only broker hiking up margins ahead of them.

Greetings,
Admiral Market will not be the only broker to raise the margin requirements. More or less I believe that there will not be a broker to keep the current margin requirements. I already know for a few more.

Most brokers just warn and remind you that the markets can be pretty volatile, but there are traditionally two election rounds. So, don't panic. I mean can the French be that misdirected if they see Trump, Boris Johnson and Erdogan. Three total blind flanges. The Dutch were smarter and didn't elect their Geert Wilders. What will the French do?

Here is a mail from HotForex I had a demo account with long ago:

Dear Client,

The first round of the French Elections is coming up this Sunday, April 23 and it’s expected to be a market-shaker!
What will the result be and what the consequences for the trading world? Analysts believe that the effects will not only impact the Euro.
Prepare your strategy and get ready to trade on this high-volatility occasion!

Warm regards,

The HotForex team