Donald Trump has defied and mocked the Washington establishment on his ride to the top of the 2016 GOP presidential field. But his emerging domestic and foreign policies show that, behind the scenes, he is starting to rely on some established Republican voices.

On immigration, Trump, a billionaire businessman who has never held public office, turned to Alabama GOP Sen. Jeff Sessions to help draft his recently unveiled campaign platform. Sessions, one of Washington’s leading foes of illegal immigration, in turn touted Trump's proposal. 

“It’s just a mainstream plan that politicians have been promising to do for 30 years,” Sessions told Fox News on Monday. “These are things that are bread-and-butter basics.” 

Trump’s proclamation on day one of his campaign that he would build a wall along the country’s southern border and “have Mexico pay” was clearly directed at the party’s conservative base, and was included in the immigration platform. But his plan, and commentary on it, also had the markings of Sessions' well-honed argument that allowing illegal immigrants into the U.S. depresses wages and takes jobs from Americans -- and that granting them a path to citizenship is tantamount to amnesty.  

“They have to go,” Trump proclaimed Sunday on NBC about illegal immigrants and children born to them in the United States. 

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That Trump and his attention-grabbing, roughly eight-week-old campaign would eventually have to focus more on policy appears inevitable. Likewise, it was only a matter of time before the Republican front-runner -- who does not keep a battalion of campaign advisers on hand -- would have to turn to some established voices for help. 

But whether he continues to reach out to them, and whether that may hurt Trump among voters drawn to his renegade-style campaign, remains to be seen. 

“Trump's supporters don't like him because of his consistency or his deep understanding of the issues,” Republican strategist Joe Desilets, managing partner at the D.C.-based political consulting firm 21st & Main, said.

“They like him because he is a flame-thrower who speaks his mind regardless of the consequences. With that said, I find it difficult to see Trump's supporters abandoning him over who his policy advisers are.”

Trump has indeed attacked the Washington establishment -- including so-called “career politicians” and the Republican National Committee. Most polls show him with a double-digit lead over his closest GOP rivals. He has also threatened to launch an independent bid if mistreated by Washington Republicans, which could severely hurt the party’s chances of winning the 2016 White House race. 

In Washington circles, Sessions is still a standard-bearer for the immigration policy right. But he's not the only GOP voice Trump is consulting. 

On foreign policy, Trump told NBC that he picks up military advice from analysts on TV including retired Army Col. Jack Jacobs and John Bolton, a former U.N. ambassador and a Fox News contributor. 

Whether Trump has personally spoken to either for policy advice is unclear. Bolton does not discuss details of private policy discussions. Jacobs, who now describes himself as a journalist, did not respond to an attempt to contact him.

But Bolton has been seen talking privately with Trump and other GOP candidates including Florida Sen. Marco Rubio and former Florida Gov. Jeb Bush on the sidelines of at least two recent gatherings -- the New Hampshire Republican Party’s “First in the Nation” Leadership Summit and the Iowa Freedom Summit. 

Trump's campaign operation itself may also be evolving. For ground-game strategy, Trump has hired long-time Republican operative Chuck Lauder to run his Iowa campaign.

Lauder is well known for helping GOP presidential candidate and former Pennsylvania Sen. Rick Santorum pull off a surprise win in the 2012 Iowa caucuses.

Trump’s immigration plan, meanwhile, also calls for overhauling the federal government’s H-1B work visa program to keep U.S. companies from what he calls importing “cheaper workers from overseas” to fill vacancies for skilled jobs.

It is an issue on which Sessions’ office has increasingly focused since helping defeat the Senate’s bipartisan immigration bill in 2013.

“One thing I like about (Trump’s) plan is that he emphasizes how this unlawful, huge flow of immigration is hammering poor people -- African Americans, Hispanics who are here struggling to get a higher wage,” Sessions also told Fox News on Monday.

In Trump’s policy papers released Sunday, the campaign also cited Chris Crane, president of a union that represents ICE agents and who is an outspoken critic of the Obama administration’s immigration policy -- often aligned with other Washington conservatives critical of that immigration policy.

The document quotes Crane arguing that ICE agents are being forced to apply Obama’s 2012 executive order on illegal immigrant children to adult inmates in jail including “serious criminals who have committed felonies, who have assaulted officers and who prey on children.”