In the run-up to Queen Elizabeth’s 70th year on the throne, British republicans said on Monday that they would start a campaign to overthrow the monarchy.

Elizabeth, 95, the world’s oldest and longest-reigning monarch, will celebrate her seventh decade as monarch next month, with Buckingham Palace announcing preparations for a four-day celebration in June.

The anti-monarchy organization Republic, on the other hand, exploited the occasion to announce that it would launch a “Not Another 70” campaign to advocate for the institution’s demise.

“While a vocal minority will want to celebrate the queen’s seventy year reign, we must all start looking to the future. The prospect of King Charles is not a happy one, and there is a good, democratic alternative on offer,” Republic’s Graham Smith said.

“It’s time to have a serious debate about our constitution, accept that Charles is not the best the country has to offer, and that as a nation we are quite capable of choosing our head of state.”

Polls indicate the vast majority of people in Britain support the monarchy and the queen herself is hugely popular. But there is not as much support for her eldest son and heir Charles, and surveys suggest there is growing republican sentiment among younger Britons.