LONDON (AP) — Efforts to unseat British Prime Minister Keir Starmer are likely to break out into open rebellion Thursday, with one potential rival expected to announce his bid for the job and another clearing the way for her to enter any future leadership contest.

Allies of Health Secretary Wes Streeting say he will make an announcement later in the day after garnering enough support from lawmakers of the governing Labour Party to challenge Starmer for leadership of the party and the government.

Former Deputy Prime Minister Angela Rayner said Thursday that she had reached an agreement with tax authorities to clear up questions about her taxes that forced her to leave the Cabinet last September. Rayner told the Guardian newspaper that Starmer should “reflect on” his position, adding that she was ready to “play my part” in any leadership election if Streeting were to trigger a contest.

Pressure for Starmer to step aside or face a leadership challenge has intensified since the Labour Party suffered disastrous losses in local and regional elections last week, underscoring concerns that voters are frustrated with the slow pace of change under the current government.

Starmer has vowed to remain in office, warning lawmakers that any leadership contest would plunge the government into “chaos” at a time it should be focused on issues like the cost of living crisis and war in the Middle East.