Voters in the city of Zurich are to decide on whether to give a financial credit to the new national carrier, swiss.
Switzerland's biggest city is to contribute SFr50 million ($30 million) towards the new airline, which was officially launched last Sunday.
If the credit package passes at the ballot box, Zurich would become the third biggest public shareholder in swiss. Federal authorities and the canton of Zurich contribute SFr600 million and SFr300 million respectively.
The new airline, which was built around the regional carrier, Crossair, and parts of the collapsed Swissair, has a capital of just over SFr3 billion.
Under a plan agreed last October, corporate sponsors are expected to take nearly two thirds of the shares in swiss, while the federal, cantonal and local authorities take the remaining third.
The main political parties in the city are divided over the issue and the arguments are similar to previous debates on cantonal and federal levels.
Supporters of the credit package - the Social Democratic Party, the Radicals and the Christian Democratic Party - argue that Zurich would benefit economically from the airline.
They say thousands of jobs around the city depend on the nearby airport and on a financially sound national airline. Supporters also see a yes-vote as a gesture of solidarity with other public sponsors.
But opponents, led by the right wing Swiss People's Party and left wing groups, say the local authorities should not get involved in a purely commercial enterprise.
They consider the business plan for the national airline too risky, saying taking a stake in swiss would put an additional strain on the city's finances.
Analysts say voters in the city of Zurich are likely to approve the credit package. Final decisions in more than half of Switzerland's 26 cantons on financial contributions to the carrier are still pending. So far, three cantons have refused to take stakes in the new airline.
Others have only approved reduced contributions. Even in a best-case scenario public sponsorship funds will fall more than SFr20 million short of the target of just over SFr1 billion originally set.
A spokesman for the national airline said the local vote in Zurich is important, but not crucial for swiss.
"From a strictly financial point of view we do not need the 50 million credit from the city of Zurich," spokesman Patrick Jeandrain told swissinfo. "But the funds are important because they would provide us with more financial means."
Significance for city
"On a more symbolic level," Jeandrain said, it is important that the whole country and Zurich in particular, stand behind the new national airline. "Because our intercontinental hub is located near Zurich," he added.
The company is confident that voters will acknowledge the significance of swiss for the national economy and for Zurich's local business community.
The airline, which entered into an association with American Alliance, operates a fleet of 130 aircraft and serves more than 120 destinations in Europe, Africa, Asia, and the Americas.
swissinfo with agencies