Scottish First Minister Nicola Sturgeon has cleared the first major hurdle for holding a new referendum on Scottish independence from the United Kingdom.

Her bid for a vote on secession won by 69 to 59 votes in Scottish Parliament on Tuesday afternoon, just one day before British Prime Minister Theresa May will initiate the process for Brexit, Britain’s impending departure from the European Union.

Brexit backlash is what drove Sturgeon and her Scottish National Party to push for another independence vote ― Scotland’s second in less than three years ― to potentially save Scots from being pulled out of the EU against their will.

Nearly two-thirds of Scottish voters opted to stay in the bloc during the historic Brexit referendum last June, when 51.9 percent of British voters chose to leave.

“We know that Brexit threatens a hugely damaging and uncertain future for Scotland,” Sturgeon said Tuesday after the vote. “This is first and foremost about giving the people of Scotland a choice on this country’s future.”

Scots rejected independence in a referendum in 2014, before Britain had announced the Brexit vote would occur. The circumstances are different now, Sturgeon insists, and therefore Scotland needs the chance to reconsider its democratic options. She wants “IndyRef2” to be held at least 18 months from now ― once the terms of Brexit are clear, but before it takes effect.

The countdown begins on Wednesday, when May will trigger Brexit proceedings by officially informing EU leaders of Britain’s intention to withdraw from the bloc. The U.K. will then have up to two years to negotiate an exit deal with the EU before it must leave.

Sturgeon’s next step in her unwavering pursuit of a new secession referendum is to win approval from British Parliament, but May says she will not grant it until the U.K. leaves the EU ― she has maintained her assertion that “now is not the time,” and that Brits “should be working together, not pulling apart.”

In a cautionary message to May, Sturgeon said that the mandate for IndyRef2 is clear, and “it would be democratically indefensible ― and utterly unsustainable ― to attempt to stand in the way of it.” She said she will seek Westminster’s approval “within the next few days.”

Scottish Conservative leader Ruth Davidson called the outcome of Tuesday’s vote “deeply regrettable,” and warned “it will only add to the uncertainty facing Scotland at this time.”

Even if Scots do get the chance to vote on their sovereignty again, leaving the U.K. in hopes of rejoining the EU as an independent nation could be a risky venture. Scotland’s readmission to the bloc would not be automatic; it would have to reapply and win unanimous approval from EU members.

Some member states, including France and Spain, have already tried to discourage Scotland from attempting to negotiate with the EU as a new state.

But Sturgeon remains undeterred.

“The people of Scotland are sovereign,” she said on Tuesday, “and they will be given a choice on their own future.”

This story has been updated with comment from Nicola Sturgeon and Ruth Davidson.