LONDON, March 28 (Reuters) – Prime Minister Theresa May will file formal Brexit divorce papers on Wednesday, pitching the United Kingdom into the unknown and triggering years of uncertain negotiations that will test the endurance of the European Union.

Nine months after Britons voted to leave, May will notify EU Council President Donald Tusk in a letter that the UK really is quitting the bloc it joined in 1973.

The prime minister, an initial opponent of Brexit who won the top job in the political turmoil that followed the referendum vote, will then have two years to settle the terms of the divorce before it comes into effect in late March 2019.

“Now that the decision has been made to leave the EU, it is time to come together,” May will tell lawmakers, according to comments supplied by her office.

“When I sit around the negotiating table in the months ahead, I will represent every person in the whole United Kingdom – young and old, rich and poor, city, town, country and all the villages and hamlets in between,” May will say.

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