Andy Burnham is meeting the leaders of the trade unions which help fund the Labour Party, as he looks to shore up support ahead of his expected premiership.

The meeting is being held at the headquarters of Unison, one of the 11 unions affiliated with the party, Unison sources have told the BBC.

In a speech on Monday, his first since launching his bid to replace Sir Keir Starmer as prime minister, Burnham suggested he wanted local communities to be given “greater public control of essential services”.

The GMB union is expected to raise this issue with Burnham, specifically on the ownership of water, as well as buying British, school support staff and equal pay, sources say.

Trade union support is an important step on the way to becoming a candidate for the Labour leadership.

Burnham announced his intention to stand shortly after being elected as the MP for Makerfield. He is so far the sole candidate, and if that remains the case he could become the next prime minister as early as 20 July.

A central point of contention between some of the unions and Burnham is the possible appointment of Ed Miliband as his chancellor.

The general secretaries of Unite and the GMB union – which both represent workers in the fossil fuel industry – have heavily lobbied against Miliband due to his policies on North Sea oil drilling as the energy secretary.

Miliband has repeatedly dismissed calls to approve new oil and gas licences in the North Sea.

Gary Smith, the general secretary of the GMB, has described the government’s net zero policies on the North Sea oil and gas industries as “shameful” and “economic madness”, and reportedly raised the prospect of a Miliband chancellorship with Burnham when they met last week, according to the Financial Times.

But Andrea Egan, the general secretary of Unison, has backed Miliband for chancellor, the Guardian reports.

The other candidate reportedly being mooted as chancellor in a Burnham government is Wes Streeting, Sir Keir’s former health secretary whose resignation contributed to his downfall.

Also among the topics which could be discussed between Burnham and the unions on Thursday is electoral reform.

Critics have long said the first-past-the-post system means candidates can be elected on a relatively low share of the vote, undermining democracy; but defenders say it means decisive results and, in theory, more stable government.

Burnham has long called for reform, telling BBC Radio Manchester during the Makerfield by-election campaign: “I do think there needs to be reform to the electoral system to enable less point-scoring, more problem-solving.”

Eight out of Labour’s 11 affiliated trade unions also have formal policy in favour of electoral reform.