MADRID, Oct 1 - Chances that Spain's Congress would pass a decree aimed at curbing the housing crisis grew dimmer on Thursday after Catalan kingmaker party Junts raised last-minute issues and requested the government devise a new proposal on the eve of a scheduled vote.

Junts, a separatist centre-right party with seven MPs, argued that the proposed measures would make matters worse by reducing housing supply. These include a ban on evictions of vulnerable tenants until 2030, a two-year rent freeze extension for existing leases, and tighter rules for short-term rentals.

"Many of the measures included will produce the opposite effect of what is intended: they will reduce the supply of rental housing, drive up prices, and make it even harder for people with limited financial means to access housing," Junts said in a statement.

Spanish Prime Minister Pedro Sanchez's minority leftist government has only 147 seats in the 350-seat chamber and relies on the support of a patchwork of smaller parties to pass legislation.

Opposition parties have already signalled that they will not support the decree, one of two crafted by Spain's Socialist government after protests sparked by the eviction of 87-year-old Maricarmen Abascal last week.

Thousands of mostly young activists camped out in Madrid's main square and other Spanish cities to protest the eviction and call for major reforms.

A second decree, which would permit automatic and indefinite renewal of rental contracts, was already expected not to pass, failing to secure the minimum support required from Spain's fractured Congress.

"I already thought the measures were insufficient and only temporary, but vetoing them is selfish and abandoning the people," Aidan, a 26-year-old wildfire firefighter, said of Junts' decision not to back the measures. "We'll keep up the encampment," he added.