Leader of the Social Democrats Christian Levrat led the charge, saying: “We are in front of a pile of s***: The relationship with the EU is worse than ever… [Switzerland needs] a serious domestic political debate on the basis of facts.”
He added: “We’ve been tangled up in mock debates for far too long.”
Mr Levrat’s comments echo the views expressed by the country’s outgoing President Doris Leuthard who called for a referendum to be held to clarify what sort of relationship, if any, the country had with the EU.
“Therefore a fundamental referendum would be helpful.”
Albert Rösti, head of the right-wing Swiss People’s party, accused the bloc of having colonial-style polices.
He said: “The EU wants Switzerland to automatically take over EU law. In disputes, the European Court of Justice should decide.
“Failure to comply may result in the EU taking penalties vis-à-vis Switzerland.
“This agreement, which the EU Commission president Jean-Claude Juncker termed a ‘friendship treaty,’ is a colonial treaty.”
He added: “Such a contract would be virtually equivalent to EU accession. Switzerland must vigorously resist here if, after centuries of independence and freedom, we do not want to lose our self-determination.”
Christian Democrats (CVP) leader Gerhard Pfister also blasted the EU’s decision, telling the newspaper Blick: “Switzerland is a free and sovereign country in the middle of Europe.
“She is not a member of the EU and should remain so.”
Mr Pfister also blasted the idea of bringing the country’s judicial system under the direction of European judges.
He said: “A framework agreement limiting the sovereignty of Switzerland with foreign judges is not acceptable to the CVP.”
Mr Pfister said: “The EU must not unilaterally weaken Switzerland’s competitiveness without knowing that it is harming itself.
“The bilateral path is the right one for Switzerland.”
Petra Gössi, who is in charge of the Free Liberals (FDP), also added her weight to the attack, saying: “The EU has to abandon the blockade policy if it is interested in good relations.”
She added: “But it is becoming increasingly clear that we need a new foundation for the contracts.
“For this, we want a self-confident and sustainable solution in which Switzerland and the EU meet as equal partners. The FDP wants legal security and market access.”
Relations between Switzerland and the EU appear to have slumped to an all-time low after Brussels offered the Swiss stock exchange access to the EU market for only one year despite recently granting the US, Hong Kong and Australia access for an unlimited time.
The commission argued that in comparison with these three countries, “the scope of the Swiss decision is much greater, as the trading of Swiss shares in the EU – and vice versa – is more widespread.”
A commission official said in Brussels: “This decision should not come as a surprise.”
The four politicians represent the political spectrum in Switzerland from the left-wing Social Democrats to the nationalist Swiss People’s party.
Before Christmas Ms Leuthard accused Brussels of “unacceptable” discrimination intended to undermine the country’s role as a financial centre.
Switzerland had expected its stock exchanges to be granted full access to EU markets after it paid €1.1bn in funding to help support the bloc’s poorer member states.
But Brussels has tied talks about granting Switzerland financial market “equivalence” to long-running political negotiations about overhauling Bern’s relationship with the EU.
The European Commission is putting pressure on Bern to accept its regulations and the role of the European Court of Justice.
It also wants to unify a swath of bilateral agreements that allow Switzerland access to the single market, so that the bilateral deals keep pace with changes to European law.