The left and centre-right of the political spectrum have warned of negative consequences if Swiss voters turn down a key labour accord with the European Union.
The vote on extending the free circulation of people to the ten new members of the EU is to be held on September 25.
A committee representing the Left and Greens on Thursday said a "yes" vote would encourage an opening of Switzerland to Europe and would also protect salary levels.
But it also called for vigilance in strict controls on possible wage dumping.
The president of the centre-left Social Democratic Party, Hans-Jürg Fehr, said he was convinced that the Swiss were not isolationist.
"They know that opening up and cooperation will bring us more benefits than disadvantages," he told a news conference in Bern.
Another member of the committee, Social Democrat parliamentarian and trade unionist Christian Levrat, argued that saying "no" at the ballot box would be a "splendid own goal".
"By obliging parliament to approve new accompanying measures, the unions and the Left have obtained the means to respect the principle whereby every person working in Switzerland must receive a Swiss salary," he added.
Another committee, representing the centre-right and calling itself "Yes to the bilateral accords" on Wednesday highlighted the importance of the European market for the Swiss economy, particularly its exports.
Parliamentarian Johann Schneider-Ammann, who is president of the umbrella organisation of the Swiss engineering association, said the accords were the "main way" to have optimum access to EU markets.
He added that the extension of the free movement to the ten new EU members, mainly in eastern Europe, was "an opportunity to be seized", all the more since measures had been put in place to protect salaries and working conditions.
Schneider-Ammann added that although there was a certain pressure on salaries, this was as a result of globalisation and increased competition and not as a consequence of the EU and its enlargement.
The committee underlined the good economic prospects of the new EU members, which indicated a rapid improvement in their prosperity and salary levels.
Parliamentarian Viola Amherd of the centre-right Christian Democrats said that in such a situation the motivation for people to migrate would be weaker.
She argued that the majority of people in the new EU states would not wish to exchange an environment which they knew for one with social, linguistic and cultural obstacles.
swissinfo with agencies
The leftist committee contains personalities from the Social Democratic Party, the Young Social Democratic Party, the Greens, the Forum for the Integration of Migrants and the unions.
There are about 100 parliamentarians in the centre-right committee "Yes to the bilaterals" from the Radical Party, the Christian Democratic Party, the Liberal Party and the Protestant Party.
The vote on extending the free movement of people to the new EU states takes place on September 25.
The ten countries that joined the EU on May 1, 2004 are: Lithuania, Latvia, Estonia, Poland, Hungary, Slovakia, the Czech Republic, Slovenia, Cyprus and Malta.
On June 5, Swiss voters voted in favour of the Schengen and Dublin accords on closer ties on security and asylum issues with the EU by a majority of 54.6 per cent.