Can a nation impose a strict ceiling on its population numbers? Switzerland faces this question on Sunday through a referendum on a proposal to limit residents to 10 million, highlighting sharp splits over immigration in the Alpine country.

The initiative comes from the right-wing Swiss People's Party, framed as a sustainability effort to reduce strain on housing, public services and the environment. Yet many see it as another step in the party's anti-immigration agenda.

Officials, rival parties, business groups and unions label it a chaos initiative. They argue it would leave hospitals and hotels short of staff, harm ties with the European Union and leave Switzerland vulnerable in uncertain times.

Since 2002, when the population stood at 7.3 million, numbers have risen sharply to 9.1 million, with 27 percent born abroad.

Direct democracy allows citizens to force nationwide votes after collecting 100,000 signatures on major issues.

Many residents cite crowded trains, high rents and climbing health costs as pressing worries.

Recent surveys point to a tight contest, with 52 percent leaning against the plan and 45 percent in favor, though many remain undecided.

Young politicians Helin Genis and Nils Fiechter share similar backgrounds yet hold opposing views that reflect the divide.

Genis, aged 31, and Fiechter, aged 29, both come from immigrant families. Genis's parents hail from Turkey, while Fiechter's mother is Canadian and he holds dual nationality.

Fiechter, representing the Swiss People's Party in Bern's parliament, says the country has lost control, with unchecked immigration eroding Swiss identity.

He links housing shortages, traffic jams, overloaded schools and stretched services directly to immigration levels.

Genis, a Social Democrat on Bern city council, rejects these claims as misplaced blame.

She states that migrants do not set rents, raise insurance costs or shape policy on housing and infrastructure.

She adds that focusing solely on migration creates division rather than answers.

Undecided voters question how any cap would operate in practice.

No other nation has attempted a hard resident limit, though China once used a one-child policy to curb growth.

The Swiss plan requires the population stay below 10 million by 2050, with action required once it hits 9.5 million.

Possible steps include tighter asylum rules and ending family reunification for foreign workers.

Reaching the cap would force withdrawal from agreements such as EU free movement rules.

Economiesuisse chief economist Rudolf Minsch warns of strained EU relations if the measure passes.

Brussels has cautioned that non-members cannot pick only the benefits of the single market while avoiding obligations like free movement.

Minsch notes the EU remains Switzerland's top trading partner and stable ties serve national interests.

Employers fear labor shortfalls and reduced access to skilled workers across Europe.

Immigrants make up half the hotel workforce, while hospitals and care homes also depend on foreign staff.

The Swiss People's Party claims immigration drives demand for more beds and school places, so limits would ease burdens.

Opponents call this unrealistic given that 20 percent of the population is now over 65.

Young workers and taxpayers are needed to support an ageing society that does not produce enough of its own, they say.

Social Democrat MP Jon Pult fears isolation in an unstable world above all.

Switzerland is boosting defense spending and seeking closer ties with neighbors despite its neutral stance.

Rising fuel prices from conflicts in Ukraine and Iran, plus US tariffs on Swiss goods, add pressure.

Pult warns that a cap risks damaging EU treaties and goodwill from Brussels.

Fiechter dismisses such concerns as scare tactics, insisting the EU would not let agreements collapse since they benefit both sides.

Fear of isolation could sway some voters.

Posters show a grinning US President Donald Trump with Russian and Chinese leaders in the background, asking if now is the time to break from Europe.

Fiechter maintains the cap protects a valued way of life for all residents.

Genis sees no merit, arguing the real issues are affordable housing, fair work conditions and strong public services rather than exclusion.

She believes the plan would harm Switzerland overall.