DUP MP Ian Paisley has backed Liz Truss to become the UK's next Prime Minister.
He said his "heart probably says" he would support the Foreign Secretary as she has been "more engaged" on unionist concerns over Brexit's Northern Ireland Protocol.
The North Antrim MP also said he believed Ms Truss "has the edge" over fellow Conservative Party leadership contender Rishi Sunak on who could win a general election.
Read more: Conservative members in Northern Ireland on what they think of final two leadership contenders
Both candidates will go head-to-head in a TV debate on Monday night in a bid to win the support of party members in the race to succeed Boris Johnson.
Postal ballots are set to arrive on Tory members' doorsteps by August 5, with a final result due to be announced in September.
Mr Paisley said both candidates "get it" in relation to unionist concerns over the Northern Ireland Protocol, which has created barriers on trade into the region from Great Britain.
But he said unionists believe Ms Truss is the candidate they could "trust the most" to press ahead with changes to the post-Brexit Irish Sea trade deal.
As Foreign Secretary, Ms Truss was responsible for introducing the contentious Northern Ireland Protocol Bill aimed at overriding parts of the agreement between the UK and European Union.
Mr Paisley said: "Because Liz Truss has been so prominent in pushing the reforms to the Protocol, I think they (unionists) would think that Liz Truss is probably the person that they could trust the most in taking that forward and delivering it.
"From the Conservative Party's point of view they have to think who can they put in office who will win them the next election, and I think that's going to be at the back of their minds, so not the Protocol, not anything else, but who will win the next election against Labour.
"And I think probably Liz Truss has the edge and the advantage. From our point of view as a political party, we will have to work with whoever is there."
Speaking on BBC's Good Morning Ulster programme, he added: "I don't have a vote in it, but I would say this.
"I think my heart probably says I would like to see Liz Truss getting it because she has been much more engaged on this issue.
"But my support doesn't really matter here nor there and the Conservative Party will be trying to get someone who will win the next election for them. I think Liz has the edge on that."
Stormont has been in limbo since February when the DUP withdrew its First Minister from the devolved Executive in protest over the Protocol.
The Assembly will sit on Tuesday to attempt for a third time since May’s election to elect a new Speaker following a recall motion by the SDLP.
But the DUP has made clear it will continue to block the election of a Speaker, preventing further Assembly business including the nomination of new first and deputy first ministers.
Mr Paisley disputed the notion that people "would have been living in utopia, not Ulster" if Stormont had been restored in recent months.
"I just think we need to just blow the whistle slightly on this story that is told that everything is crumbling apart because of the last few weeks since the election," he said.
"Let's resolve this issue of the Protocol, power-sharing will be restored almost immediately and we will have an Executive again and we can get down to those problems."
The MP urged members of the House of Lords not to "procrastinate" on the Northern Ireland Protocol Bill.
He said: "We're down the road on this issue of solving the Protocol at Parliament. Let's make sure that we get it through Parliament.
"I would say to the peers in the House of Lords, for every day that they procrastinate and delay will be a day that the Assembly will not be meeting and the Executive will not be meeting."
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