President Donald Trump said Friday that he's considering using military resources to finish construction of his long-promised border wall instead of relying on Congress to fund the project through the Homeland Security Department's budget.

He also wouldn't eliminate the possibility of a government shutdown if Democrats continue to confound his efforts to appropriate money for the project on the U.S.-Mexico border.

'We have two options,' he told DailyMail.com aboard Air Force One as he flew from Billings, Montana to Fargo, North Dakota. 'We have military, we have homeland security.'

He was asked specifically about using the Army Corps of Engineers as a taxpayer-funded construction crew.

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President Donald Trump said Friday that he's considering using military resources to finish construction of his long-promised border wall, as he spoke to the press on Air Force One, above on Friday

'We have two options,' he told DailyMail.com aboard Air Force One as he flew from Billings, Montana to Fargo, North Dakota. 'We have military, we have homeland security'

Trump said he would prefer to fund the ambitious construction 'the old-fashioned way – get it from Congress – but I have other options if I have to.'

He's seeking about $25 billion.

The possibility of diverting Pentagon funding and assets to build a border wall is a hole card the president is holding but has never directly acknowledged before.

Two Defense Department officials told DailyMail.com in August that the Army Corps of Engineers could take on the task.

'They build levees that hold back massive walls of water,' one said of the agency. 'They can build one to hold back drugs and human traffickers.'

The White House appears headed for another confrontation with Congress over an increase in funding for the project after securing $1.6 billion for 2007 and the same amount for this year.

A Homeland Security border patrol vehicle monitors the border area where prototypes of US President Donald Trump's proposed border wall are standing in this November 2017 file photo

A senior White House official said Thursday that the money was 'basically a down-payment on the thing'.

The possibility looms that the president will refuse to sign the next federal budget, due September 30, if lawmakers don't go along with more installments. That would trigger a government shutdown.

'If it were up – I don't want to say "up to me," because it is up to me – I would do it,' he said aboard Air Force One, 'because I think it's a great political issue.'

But he said some Republicans in Congress, facing tough re-election fights, have counseled more patience.

'They have races, they're doing well, they're up,' Trump explained. 'And you know, the way they look at it: might be good, might be bad.'

Typically the party in power, in this case the GOP, would shoulder most of the blame for interrupted government services. National security and military operations wouldn't be affected.

Trump said he would prefer to fund the ambitious construction 'the old-fashioned way – get it from Congress – but I have other options if I have to.' he is pictured above speaking with the press on Air Force One on Friday

The Army Corps of Engineers are seen above in this file photo repairing damage to the middle breakwater caused by Hurricane Marie in Long Beach, California, in January 2015

Thursday night in Billings, he told a Fox News Channel interviewer that 'we need Republicans elected in the midterms'.

'We are getting the wall done. But I've had so many people, good people, great people – they would rather not do [it] before [November]. They'd rather do it right after the election.'

Trump said he still wants to persuade Congress – preferably one reinforced with more Republicans – to write the checks he wants.

'Politically speaking, I'd rather get it through Congress. If we don't, I'm looking at that option very seriously,' he said aboard Air Force One on Friday, referring to the Defense Department.

In Sioux Falls, South Dakota on Friday evening the president assured a crowd of about 600 supporters that 'we're building the wall!'

'It works so easily!' he said. 'They say walls don't work? Tell Israel.'