Leading Republican candidate for the White House Donald Trump hasn't officially begun scouting running mates - the first primary is still six months away.

Two of his 2016 competitors come to mind for the position, however: Ben Carson and Ted Cruz.

Trump's campaign said he has 'cordial' relationships with both men based on 'mutual respect.'

An ex-aide to Trump, Roger Stone, was also seen meeting with Carson's campaign chief Jake Menges yesterday in New York. Stone says he did not set up the meeting at the behest of Trump, however.

Scroll down for video

Donald Trump and Ted Cruz are pose together for a photo after their July 15 meeting at Trump tower. Cruz met with the billionaire businessman last month in New York City. They talked about going to the border together, but it didn't work out

Trump is pictured here on July 23 at the U.S.-Mexico border. Both his campaign and Cruz's have confirmed that the Texas senator was supposed to be on the trip as well, but a scheduling conflict - Senate votes - foiled their plans

Stone told DailyMail.com that he believes in 'citizen action' and met with Menges of his own volition because he thinks Carson would be a good fit on a Trump ticket.

He stressed that the meet-up was 'not authorized' by Trump and he no longer works for the real estate mogul.

'I love him. I love him,' he said, 'but I'm not working for him.'

Trump and Stone parted ways two weeks ago over disagreements about the direction of the campaign. Stone says he resigned. Trump says he was fired. Whatever the case, the end result is that Stone is now a free agent.

'I answer only to myself,' he said today.

Even though he is no longer affiliated with Trump's campaign for president, he still wants to see him in the Oval Office.

He's stepped in as an unofficial surrogate for Trump, making multiple media appearances this week to defend his controversial immigration plan that would end birthright citizenship for the children of illegal immigrants.

'I will go anywhere, do anything I can to promote the election of Donald Trump,' he told DailyMail.com.

Trump, he says, 'is the only man with the fortitude and the vision and the passion to take on a corrupted political system.'

'The system's broken, both parties are in on it. Our government's controlled by the special interests,' the ex-lobbyist and alum of Richard Nixon's administration said. 'I've seen the system up close, it's broken. It's corrupted.'

Stone, who noted that he's had a hand in eight presidential elections, has taken it upon himself to begin vetting a No. 2 for Trump.

'I don't think that Donald has thought about a running mate yet, and frankly it would be presumptuous for him to do so,' Stone said. 'He's focused on winning the nomination, and then winning the election.'

Still, he added, 'it's never too early to start thinking about the big picture.'

Courting Carson: an ex-aide to Trump, acting on his own, is trying to get Ben Carson to sign on as Trump's No. 2. Trump has said that he likes both Carson and Cruz and would consider having them on his ticket

Trump has openly praised Cruz and Carson, telling NH1 after he was asked about possible running mates, 'I like Ted Cruz. I like Dr. Carson. They’ve been very supportive of me.'

He's also said he'd like to have Oprah at his side.

'I think Oprah would be great. I’d love to have Oprah,' Trump said in a June appearance on ABC News. 'I think we’d win easily, actually.'

Trump said last week that he'd 'consider' sticking a woman on the ticket, as well.

'I am all for the concept. It would have to be the right person, and I’m not going to go into who that would be right now,' he said told the Chicago Sun-Times. 'But I have great respect for women. I have great respect for women who are executives in my company. I have great respect for women’s judgment.'

A Washington outsider like Trump, Carly Fiorina has been suggested as someone who fits that bill.

The Carson campaign did not return DailyMail.com's request for comment on the matter, but Carson, a retired neurosurgeon who hails from Baltimore, Maryland, and has never held political office before, either, has said he'd likewise consider adding Trump to his team should he become the nominee.

'All things are possible. Absolutely,' he said during an interview with Fox News' Neil Cavuto earlier this summer after complimenting Trump as 'a very smart' and 'fun guy.'

Former Richard Nixon aide Roger Stone, pictured here in his office a year ago, met yesterday with Ben Carson's chief campaign hand. 'It's never too early to start thinking about the big picture,' he told DailyMail.com

Cruz met with the billionaire businessman last month in New York City, and a senior adviser to Trump told DailyMail.com the two had planned to visit the United States' border with Mexico together in July.

A scheduling conflict -Senate votes - prevented the Texas senator from hosting Trump, however.

A spokesman for Cruz says the lawmaker proposed the border trip during their meeting at Trump Tower in New York.

'We were talking about immigration and then Ted said to Mr. Trump, "you should come to the Texas border. Be my guest and we’ll go together," ' spokesman Rick Tyler told the Washington Post.

A sources close to Trump told the Daily Beast says that the Republican politicians talk on the occasionally and have gotten together four other times aside from the Trump Tower visit.

Cruz has had nothing but praise for Trump throughout the campaign and is backing his immigration plan. He said yesterday on the Michael Medved radio show that he too believed that 14th amendment's guarantee of automatic citizenship should be limited to children who parents are legal U.S. residents.

'I welcome Donald Trump's immigration proposal. Virtually every element in the proposal he submitted is contained within legislation that I filed years ago in the Untied States Senate.'