LONDON (AP) — Britain's Labour Party has gone to court in a bid to prevent tens of thousands of new members from voting in the party's leadership contest.

The country's main opposition party has descended into turmoil, with lawmakers trying to unseat leader Jeremy Corbyn. The party's more centrist members consider, Corbyn, a 67-year-old left-winger, unelectable.

He is facing a challenge from legislator Owen Smith in an election that will be decided by party members and supporters next month.

The party ruled that only members of at least six months' standing could vote. Five Labour members challenged the decision, and an earlier court ruled in their favor.

Party general-secretary Iain McNicol asked the Court of Appeal on Thursday to overturn the judgment, which affects almost 130,000 people — many of them thought to support Corbyn.