LISBON, Portugal — Portugal’s president has refused to sign for the second time a parliament-sanctioned bill allowing euthanasia and physician-assisted suicide, arguing the wording is imprecise and effectively shelving the piece of legislation until a new parliament and government are chosen early next year.

Marcelo Rebelo de Sousa, the staunch Catholic who has remained popular for more than five years as head of the Portuguese state, already showed reservations over the bill’s first version when he sent it to the country’s top court earlier this year.

The Constitutional Court rejected it because what it said was a lack of “indispensable rigor.”

This time, the president is returning the reworded law to the national assembly, according to a statement posted on the Portuguese presidency’s website late on Monday, arguing that further clarification is needed in “what appear to be contradictions” regarding the causes that justify resorting to death with medical assistance.

Euthanasia is when a doctor directly administers fatal drugs to a patient. Medically assisted suicide is when patients administer the lethal drug themselves, under medical supervision.

Whereas the original bill required “fatal disease” as a pre-requisite, the president’s argument followed, the renewed version mentions “incurable” or “serious” disease in some of its formulation. No longer considering that patients need to be terminally ill means, in De Sousa’s opinion, “a considerable change of weighing the values ​​of life and free self-determination in the context of Portuguese society.”

By returning the bill to lawmakers, De Sousa is effectively delaying any progress until a new parliament is chosen in a snap election scheduled for Jan. 30. The assembly is set to be dissolved on Dec. 5 after division among an array of left-wing parties led late it in October to reject the minority Socialist government’s proposed budget for next year.

Left-of-center parties had sponsored the euthanasia bill, as they did with laws allowing abortion, in 2007, and same-sex marriage, in 2010, in the mostly Catholic country.