has been reached, the deal cannot be amended — it goes to a straight up-or-down vote. One big point of this system is to allow the US to negotiate without the threat of Congress changing an agreement after it has been, at long last, reached with trading partners.

There is a strong case for not making the US's full positions public.

"As soon as you reveal your position and put it in print, then it's much more difficult to modify it and be flexible later," Gary Hufbauer, senior fellow at the Peterson Institute for International Economics, explained to me in November. "It's a negotiation, and everyone has to compromise to some extent."

But critics like Sanders aren't really just complaining about the process. What's driving them are worries about the deal'sItaly anti-immigration rally draws thousands in Rome Published duration 28 February 2015

image copyright Reuters image caption The Northern League protest comes as polls suggest that it is gaining support for its attacks on austerity and immigration policies

Thousands of supporters of Italy's Northern League have poured into one of Rome's biggest squares for a rally against immigration, the EU and Prime Minister Matteo Renzi's government.

League leader Matteo Salvini accused Mr Renzi of substituting the country's interests to those of the EU.

He also criticised the government's record in dealing with Romanian truck drivers, tax, banks and big business.

A large counter-demonstration against Mr Salvini was also held in Rome.

Opinion polls suggest that Mr Salvini is rapidly gaining in popularity.

They show him as being second only to Mr Renzi, prompting some to