Tony Blair's anti-Brexit speech attacked by both Remain and Leave campaigners.

Green Party leader calls speech "staggeringly unhelpful."

Few major politicians still willing to speak up for staying in EU.

Blair is filling a pro-Remain void left by his successors.

LONDON — Former Prime Minister Tony Blair's speech today, in which he called on Britain to "rise up" and block Brexit, went down like a parachute filled with bricks among both Brexit and Remain campaigners.

The foreign secretary Boris Johnson called on the public to "rise up and turn off the TV" as the former PM gave his speech, while the pro-EU Green party MP Caroline Lucas described his intervention as "staggeringly unhelpful.

The view among many Remain campaigners is that Blair, who was Britain's Prime Minister from 1997 to 2007, is precisely the wrong person to be leading this campaign.

"For this former Prime Minister, and fully paid up member of the establishment, to jump in on this debate will only harm the fight against an extreme Brexit," Lucas said.

"Though I agree with much of what Blair said — and back his defense of free movement in particular — he simply isn’t the right person to be saying it."

Right message, wrong messenger?

This idea that Blair has the right message but is the wrong messenger has long been popular on the left as have attempts to blame Blair for Brexit.

But while it is tempting to lay all the blame for Britain's current predicament on somebody who left Downing Street a decade ago, the reality is that Blair is only stepping into a vacuum created by his successors.

Whether it be the current Prime Minister Theresa May, who campaigned for Remain but is now leading the charge for the hardest of "hard Brexits," or Labour leader Jeremy Corbyn and his shadow chancellor John McDonnell, who sometimes struggle to contain their glee at the prospect of leaving the EU, it is Britain's current crop of leading politicians who have left the battlefield clear for the Brexiteers.

Whether it's fear in the face of press attacks on anybody judged to be "blocking" or "frustrating" Brexit, or simply a lack of talent or profile among other well-known pro-European politicins, the political debate on Brexit in the UK has become increasingly one-sided.

It is easy to forget now, but this time last year every single major party was in favour of remaining in the EU, the Single Market and retaining freedom of movement. And yet now there is not a single household name in British politics, with the exception of Blair himself, who is still willing to stand up in their defence.

Blair may not be the right messenger to change all of this. He may not even have the right message. But for pro-Europeans who still want someone to stand up against a "hard Brexit"— there is only one question.

If Blair isn't the right person to lead the charge, then who is?