Spanish Prime Minister Pedro Sanchez's Socialists are hoping to show Catalonia has moved past its independence fixation by winning Sunday's regional vote and defeating separatist leader Carles Puigdemont.
Polls opened at 9:00 am (0700 GMT), with voters casting their ballots to elect 135 lawmakers in the Catalan parliament in this wealthy northeastern region of some eight million people.
Surveys suggest Sanchez's Socialists are set to win the most votes, ahead of Puigdemont's hardline separatist JxCat and its rival ERC, led by current regional leader Pere Aragones.
Polls close at 8:00 pm with results due out several hours later.
"My sense today is that we are entering a new important stage in Catalonia," said Salvador Illa, head of the Catalan Socialist party on casting his ballot.
On the streets, voters agreed the election would likely change the leadership of the region, which has been dominated by separatists for the past decade.
"I'm sure the Socialists will win and that will change the ruling majority. But I don't think the situation will change much really," said Xavier Cusi, 51, who works in banking.
And 31-year-old Ainhoa Matos, who works in the insurance industry, told AFP she hoped the outcome would give a greater voice to those who weren't pro-independence.
"The independence issue has calmed down a lot so people are less on edge," she said.
"People like me who are not pro-independence have not had enough of a voice or representation so I hope that can change."
For Sanchez, seizing Catalonia from the separatists would be a major victory in his efforts to turn the page on the crisis sparked by the secession bid.
It would also let him effectively restart his latest term in office, which began in November but has been soured by bitter right-wing opposition and a graft probe into his wife that almost prompted his resignation last month.
Since becoming premier in 2018, some nine months after the October 2017 failed Catalan separatist bid, Sanchez has sought to "heal the wounds" caused by the unprecedented political crisis.
In 2021, he pardoned the separatists jailed over the secession bid.
And in November he began pushing an amnesty bill for those still wanted by the justice system in exchange for key separatist backing in parliament that let him secure a new four-year term in office.
The bill is in the Senate and due to become law in the coming weeks, allowing the return of Puigdemont, 61, the Catalan separatist leader who oversaw the independence bid then fled to Belgium to avoid prosecution.
The controversial measure has been adamantly opposed by the right and far-right.
Although the Socialists won the most votes during the last regional election in February 2021, Illa failed to piece together a governing majority.
The separatist parties clubbed together to form a 74-seat coalition.
Despite the polls, Puigdemont is hoping for a strong showing in the vote that will allow him to be reelected Catalan leader and return home triumphantly once the amnesty has become law.
Unable to enter Spain, where he is subject to an arrest warrant, he has been campaigning in southern France. He has vowed to retire from politics if he fails to win.
Despite being in power for the past decade, the Catalan separatist movement is deeply divided with JxCat sharply at odds with its more moderate rival ERC.
The picture has been complicated by the recent emergence of the new ultranationalist Catalan Alliance which is expected to win several seats.
Surveys suggest the Socialists will win around 40 seats, so they will need to seek allies to reach the 68 required for a governing majority.
One possible alliance would involve the far left and ERC, in what would likely cause a damaging implosion within the independence movement.
