After that, he said, “we have a third instrument, which we don’t want to use today, which is elections as a plebiscite” on independence, which would most likely leave the regional Parliament with a more hard-line majority of secessionist lawmakers.

Mr. Mas has previously said that “there is no Plan B” to the scheduled Nov. 9 vote on separation.

Calling a Catalan parliamentary election is only a last alternative, he said in the interview, kept “in a drawer that is closed at the moment, but not empty.” He added, “This drawer can only be opened if there is a consensus among the political formations that are pro-independence — and at this moment there isn’t.”

Mr. Mas said he did not envisage resigning even if Catalans could not vote on schedule. But a failure to hold the vote would be a major setback for Mr. Mas.

The Catalan leader has fanned expectations for independence among Catalans since a falling-out with Spanish leadership two years ago, after Mr. Rajoy rejected a Catalan request to reduce its fiscal contribution to a Spanish system that redistributes tax revenue from rich to poor regions.

That fiscal dispute coincided with hundreds of thousands filling downtown Barcelona to push for independence on Catalonia’s national day. Catalonia has 7.5 million people, or 16 percent of Spain’s population, and it is Spain’s most powerful economic region, accounting for 19 percent of the national output.

Catalonia’s bitterness over Spanish leadership remains. Mr. Mas said Catalans were entitled to feel without even “a minimum of confidence that the institutions of the state act fairly” toward the region.

“I’ve evolved just like the majority of the Catalan society,” Mr. Mas said Tuesday. "I don’t believe anymore in the Spanish state of the 19th and 20th century because that is as a state in which we tried to do everything possible to fit in well and we didn’t manage.”