LONDON (Reuters) - British Prime Minister Theresa May faces increased pressure to quit after failing to lead the country out of the European Union on schedule, with members of her own Conservative Party calling for a more pro-Brexit replacement.

British Prime Minister Theresa May leaves after a news conference following an extraordinary European Union leaders summit to discuss Brexit, in Brussels, Belgium April 11, 2019. REUTERS/Yves Herman

May has promised she will resign to let someone else negotiate Britain’s future relationship with the EU, but she wants to be the one to deliver Brexit.

So, can her party force her to go sooner than she wants to?

FORMAL LEADERSHIP CHALLENGE

Conservative Members of Parliament cannot use the party’s formal process to challenge May until December because they tried and failed to oust her in December 2018.

The rules of the process state that May is immune to further challenge for 12 months from the date of any failed leadership challenge.

VOTE OF CONFIDENCE

Parliament can vote on whether it has confidence in May’s government. If a majority of lawmakers decide they do not, she could forced to step aside.

After losing a vote of confidence there are 14 days in which she could try to retain power by winning another confidence vote. In this period, the opposition Labour Party can also try to form their own government.

A general election is called if no government with majority support in parliament can be formed after 14 days.

In January this year May survived a vote of confidence called by Labour leader Jeremy Corbyn. But there are no rules preventing Labour from calling another one at any time.

To succeed, a handful of Conservative MPs or lawmakers from the allied Democratic Unionist Party, would need to either abstain or vote with the opposition to topple the government.

Some pro-Brexit lawmakers have hinted they might be prepared to take this radical step, but it is unclear whether this would materialize in the event of a vote being called.

Losing a confidence vote would not automatically force May to resign as leader of the Conservative Party, but politically it is unlikely she would seek to carry on in the role.

PEER PRESSURE

In the absence of a formal route to get rid of May that does not risk a general election, Conservative lawmakers are looking at alternative ways to apply pressure.

May previously said she was not prepared to delay Brexit beyond June 30, but she has now agreed with the EU that Britain could remain a member until the end of October. These words are already being used to make the case that she has to stand down.

Some lawmakers have asked the internal committee responsible for carrying out Conservative leadership contests to collate letters of no confidence in May and present them to her as an indication that she no longer commands the support of her party.

The Daily Telegraph reported that lawmakers are also exploring whether the rules which currently protect May from a formal challenge can be altered. The newspaper reported that a petition signed by 10,000 grassroots members could be enough to trigger the process of changing internal party rules.

Dissatisfied members are also looking to the results of local authority elections in early May, and potentially European Parliament elections later in the month. If the party suffers heavy losses, the results would likely be used as evidence that the party needs a change of leadership.