The national election in Britain on Thursday will bring a new parliament to power and may lead to a change at the top if Prime Minister Boris Johnson’s Conservative Party doesn’t fare well with voters.

Johnson called the early election in hopes of gaining lawmakers to support his Brexit policy. Here is a look at how various election outcomes are likely to shape the difficult Brexit process.

Johnson's Conservatives win a clear majority

If Johnson achieves his goal, the new parliament is likely to move quickly to pass the Brexit withdrawal agreement the prime minister reached with European Union leaders.

Johnson says all of the Tory candidates in the running back his divorce deal, so a clear majority would give him a good shot at reaching his goal of taking Britain out of the EU by the January 31 deadline.

If that happens, little would change immediately since the agreement includes a transition period for the UK to negotiate a new trade arrangement with the EU. During the transition, Britain would continue to follow EU rules and regulations, and freedom of movement between EU nations would continue.

The next crunch time could come at the end of 2020. Johnson has said he would not extend trade talks past next December, indicating Britain would leave without a new trading arrangement in place rather than continue the talks. Most experts think it would take longer than one year for the two sides to reach an accord.

Johnson's Conservatives fall short of an outright majority

Emerging from the election without control of more than half of the seats would frustrate Johnson’s chief purpose in calling the election and cast the Brexit outcome in doubt. It’s possible he could form a coalition with a smaller party that might give him the votes needed to pass his Brexit divorce bill.

It’s also possible a Labour-led coalition with the Scottish National Party and the Liberal Democrats could form a government, most likely with Labour leader Jeremy Corbyn as prime minister.

If this happens, Corbyn is expected to try to implement his party’s two-part Brexit plan: negotiating yet another withdrawal agreement with EU leaders within three months followed by a voter referendum within six months.

The British public would be asked if it prefers enacting the new deal to proceed with Brexit or stopping the Brexit process altogether by remaining part of the EU. Corbyn says that as prime minister, he would remain neutral in the referendum.

Corbyn's Labour Party wins a clear majority

Pollsters suggest it is unlikely Labour will win a parliamentary majority but if that happens, Corbyn would have strong backing for his party’s Brexit road map. One potential problem is that leaders of other EU countries, weary of how Brexit has dragged on because of a long stalemate in British politics, have said they are unwilling to renegotiate the withdrawal agreement they already have with Johnson’s government.

However, that could change if an entirely new government comes to power, especially since the prospect of Labour’s promised referendum creates a real possibility that the entire Brexit process could be scrapped.