LONDON -- The United Kingdom is due to leave the European Union on March 29 next year. Though Britain voted in 2016 to exit the bloc, how -- and even if -- that will happen remains unclear. The U.K.'s future relationship with the EU is also uncertain.

Here are three possible scenarios:

The government's proposal passes

The U.K. government, led by Prime Minister Theresa May, has been negotiating with the EU for over a year. On Wednesday, it released its proposed withdrawal deal. The transitional deal has been criticized by those on both sides of the debate in Britain, but if it is approved, it will be the only legal agreement between Britain and the EU until another one is negotiated after March.

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One of major sticking points in any Brexit scenario is the border between the Republic of Ireland (which is part of the European Union) and Northern Ireland (which is a part of the United Kingdom). There is no hard border -- an arrangement that came after decades of violence during which Northern Irish nationalists fought against loyalists for a united Ireland, independent of the U.K. There is concern that a hard border could reignite tensions.

The government's draft deal would ensure continued free movement of goods and people between Ireland and Northern Ireland by committing Northern Ireland to the EU's single market trade and customs rules. In order to make that work, the rest of the U.K. would also adhere to the EU's single market rules for goods, as well as some of its some customs regulations for an undefined period of time.

Critics have said that would effectively leave the U.K. subject to the same EU regulations as before Brexit, except it would no longer have any power in the bloc.

Other parts of the deal call for the U.K. to honor its financial commitments to the EU for at least the next two years. The deal also includes protections for EU citizens living in Britain and a transition period lasting until at least 2020, during which time future trade agreements could be negotiated.

A number of government officials have resigned over the proposed deal, and some members of Theresa May's ruling Conservative Party have called for a vote of no confidence. If enough Conservative lawmakers make similar calls, there could be a vote for a new party leader, which would force May out of her position as prime minister.

"No-deal" Brexit

If no agreement between the British government and the European Union is reached as of March 29, the U.K. will simply cease to be in the bloc. The terms of its trade with the EU would then be set by World Trade Organization (WTO) rules.

EU countries enjoy tariff-free trade with one another. Without a U.K.-EU deal, tariffs would come into effect after Brexit.

Some economists say a "no-deal" Brexit would cost each member of the British public approximately 800 pounds (about $1,000) per year, given the expected higher prices for goods. However, hardline Brexit supporters argue that it would be best for the U.K. in the long run, as fewer commitments to Europe would make it easier for Britain to negotiate direct trade deals worldwide.

A no-deal Brexit could also cause delays at borders, as new customs agreements with nearby countries in Europe would take time to negotiate and implement.

A second referendum

Some in Britain, including lawmakers on both sides of the debate, have been calling for a second public vote on any deal that the U.K. Parliament approves. If a new referendum is called, it is possible that the government could include an option on the ballot that would essentially give voters another chance to reject Brexit completely.

Late last month, about 700,000 people marched through London in support of a grassroots campaign called "People's Vote," and three of the four former prime ministers who are still living have come out in support of a second referendum. The EU, for its part, has said it would be open to the U.K. reversing its decision to leave.

Theresa May has, however, repeatedly ruled out the possibility of a second vote on Brexit, saying the people have already spoken.

"As far as I'm concerned, there will not be a second referendum," she told reporters late Thursday.

She said her government's proposed "deal delivers what people voted for, and it is in the national interest. ... If we do not move forward with that agreement, nobody can know for sure the consequences that will follow."