Pensions secretary thought to have not yet decided on backing any candidate

Allies of Amber Rudd played down rumours she plans to join Boris Johnson in a Conservative party leadership “dream ticket” to unite the Brexiter and remainer wings of the party, as the manoeuvrings to succeed Theresa May gained pace.

With moves to oust the prime minister expected to reach a crescendo if she agrees a longer-term delay to Brexit with the EU at a Brussels summit this week, the idea of a so-called “Bamber” joint bid has been floated, potentially uniting the work and pensions secretary with the former foreign secretary.

Rudd is known to be happy to be a standard-bearer for remain-minded opinion in the race to succeed May, but is being seen more as a kingmaker than a likely winner herself, mindful of both the likely preference of Conservative members for a Brexiter as well as the tiny 346 majority she holds in her Hastings constituency.

Brexit: furious Tories will try to oust May if UK fights Euro elections Read more

Several Sunday newspapers floated the idea, touted by unnamed supportive MPs, that Johnson would supply the necessary star power with the membership and voters, with the backing of Rudd bringing round sceptical MPs and acting as a brake on his more colourful plans.

But it is understood that Rudd is by no means signed up to the plan and has not decided on supporting any particular candidate.

Facebook Twitter Pinterest Amber Rudd leaving 10 Downing Street. Photograph: Sean Smith/The Guardian

An ally of the former home secretary said Rudd’s focus was on her so-called One Nation Group of moderate Tories, said to comprise of around 40 MPs intent on making sure any future leader would not pull Britain from the EU without a deal.

They said: “She is not interested in her own status, but rather that her beliefs are properly represented.”

A colleague of Johnson did not explicitly endorse the plan, but was also at pains to stress perceived links between the pair: “Boris is a one-nation Tory and wants to build a broad church for the party.”

A tie-up with Rudd, even unofficially, would be seen as a chance for Boris to gain a step on expected leave-minded rivals for the leadership, including former Brexit secretary Dominic Raab and his successor Stephen Barclay.

Also seeking support from that wing of the party will be Michael Gove, the environment secretary, and the international development secretary, Penny Mordaunt, as well as born-again Brexiters such as Jeremy Hunt, the foreign secretary, and the home secretary, Sajid Javid.

The Guardian view on May’s Brexit offer to Corbyn: years too late | Editorial Read more

The remainer end of the race is currently less congested, in part because hopefuls realise that the party electoral system – whereby a final two whittled down by MPs are put to a vote of the strongly leave-oriented membership – does not favour such views.

Their ranks were nonetheless potentially increased by one on Sunday when the former education secretary Justine Greening, now a strong supporter of a second referendum, indicated she could well compete.

“I’d consider it,” Greening told the ITV News podcast Acting Prime Minister. “I don’t know when the leadership contest will happen but for me [the party] has always been a vehicle for changing Britain for the better, simple as that.”

Facebook Twitter Pinterest Justine Greening says she would consider throwing her hat in the ring for Tory leadership. Photograph: Will Oliver/EPA

Asked if she might be particularly tempted to try her luck if the candidates did not include any centrists, Greening said: “That would be one of the reasons why I might do it.”

Greening was dismissive of the idea of a staunchly pro-Brexit team, for example Johnson and Jacob Rees-Mogg, who chairs the European Research Group, which represents strongly leave-minded Tory backbenchers.

“I don’t think it would be a successful team,” she said. “You’re not going to win elections by fishing in a voter pool that probably represents about 30% of the country.”

Rees-Mogg, who has so far refused to say who he will back when May departs, as the prime minister has pledged to do when a Brexit departure plan is finalised, had praise on Sunday for both Johnson, the former mayor of London, and for Rudd.

“I think very highly of Boris Johnson, who managed to win in London twice in a Labour area – [he] has a great connection with voters,” Rees-Mogg told Sky News’s Sophy Ridge on Sunday show.

“He is a clear Eurosceptic but otherwise is very much in the middle of the Conservative party. He is not particularly a factional character beyond the European issue and therefore I think could unite the party and win an election.”

He called Rudd a person of “first-class capabilities”, adding: “There will come a time, though we may find this difficult to believe at the moment, when there are other things to talk about than Europe, and at that point we will need all the talents that are arrayed within the Tory party, not just those of Brexiteers.”