Washington: President Donald Trump said Sunday that he would demand that the Justice Department explore whether it or the FBI “infiltrated or surveilled the Trump Campaign for Political Purposes” - perhaps signaling the start of a showdown between the nation’s chief executive and its federal law enforcement apparatus.

After several tweets railing against the year-old special counsel probe into his campaign, Trump wrote, “I hereby demand, and will do so officially tomorrow, that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes - and if any such demands or requests were made by people within the Obama Administration!”

The tweet seemed to be a response to recent reports about the FBI using a longtime intelligence asset to advance its investigation into Russian election interference. Trump and his allies have seized on the use of the asset to claim that the FBI has spied on his campaign.

The president’s impending demand is significant in its own right: the nation’s chief executive ordering an investigation into the investigation of his campaign. But it also could presage more important developments.

House Intelligence Committee Chairman Devin Nunes, R-Calif., has sought documents on the FBI’s use of the asset and, so far, has been rebuffed by Justice Department leaders, who worry that exposing the source or the source’s work could put him in danger. The president could order the department to hand over the materials, over its objection, potentially sparking significant backlash among top officials there and in the broader intelligence community.

Law enforcement had considered the source’s identity so sensitive that FBI had been working over the past two weeks to mitigate the potential damage if his name was revealed, according to several people familiar with the matter. It is possible that officials could resign in protest or refuse the president’s order and force him to fire them.

But the president’s tweet also left open the possibility that such a conflict could be averted.

Justice Department Inspector General Michael Horowitz announced in March that he would explore controversial applications to surveil former Trump campaign adviser Carter Page, along with the department’s relationship with a former British intelligence officer who provided information cited for those requests. That review will assess whether the FBI and the Justice Department complied with the law and their own policies in requesting and carrying out the surveillance. Horowitz also said that he would examine other matters that might arise from his work.

It is possible that Horowitz’s work might have naturally led him to look at the FBI’s use of the confidential source, who had contact with Page, in the Russia investigation. The Justice Department also would not necessarily chafe at an internal look at its conduct. A Justice Department spokeswoman offered no immediate response.

In an interview with The Washington Post, Rudy Giuliani, the president’s attorney, said Trump was “doing what the president should do. He’s telling the Justice Department the obvious, which is — they should turn over information gleaned from this source.” But he offered less-than-clear answers on what the president’s ultimate directive would be.

Asked whether the president wanted the documents released, Giuliani responded, “Yes, he wants them released in this case to Congress.” But later in the conversation, Giuliani seemed to note that the president had not yet given a formal order. He said he expected a letter would be issued Monday.

“He’s not commanding them at this point but asking them to reveal the substance of this and clear it up,” Giuliani said, adding: “We think that’s only fair. If they don’t do it, he’s the president, the executive branch of a government that’s being maligned. He has the right to say, ‘Straighten it out.’ “

Giuliani said he was not worried about that sparking a possible crisis at the Justice Department, remarking, “I have a hard time believing they won’t go along. They have to eventually reveal something about this. This is a serious issue.”

He conceded, though, “They may want to put some strictures on it, like it has to be confidential, or they don’t give the name but they give the information. If they don’t want to do anything, it’s a serious problem and far worse than we even believe.”

Giuliani said the president’s tweet was driven in part by the fact that the source is “all but revealed” - pointing to accounts in the New York Times and The Post, which detailed how a retired American professor who was a US intelligence asset met with three Trump advisers during the campaign.

“It’s obvious, reading in between the lines, that the person has no incriminating information of any kind because there is none to be had,” Giuliani said. “We’d like that to be cleared up before we even approach the idea of doing an interview,” referring to an interview between the president and special counsel investigators.

Trump’s congressional GOP allies reacted positively on Sunday to the president’s request, but they seemed to view his tweets as a sign of solidarity, not a guarantee that they will soon acquire the Justice Department documents they have been seeking for months.

In emails and phone calls Sunday afternoon, GOP lawmakers close to Trump conferred and tried to interpret his position. They wondered, in particular, whether he would forcefully demand the Justice Department to hand over documents to Congress or whether he would simply push the department to eventually share more information from its ongoing probes led by its inspector general, according to three people familiar with the discussions.

There was also concern among Trump-aligned lawmakers that White House Chief of Staff John Kelly and White House counsel Donald McGahn may be trying to “water down” the president’s position as a way of avoiding a potential crisis over highly sensitive materials that Justice has long been wary of releasing, according to one person close to those Republicans.

“What’s in the letter on Monday and what it tells DOJ to do is going to be everything for us. Not the tweets,” said the person, speaking on the condition of anonymity to talk about a topic the person was not authorized to discuss publicly.

Kelly and McGahn have been point people in recent weeks as the department has dealt with ongoing congressional demands from Nunes about the activities and role of the secret FBI source, among other issues.

Stephen Vladeck, a law professor at the University of Texas at Austin, said the latest dust-up seems to be “less about the underlying dispute over document disclosure and more about the naked politicisation of a law enforcement investigation by the White House.” He said that while Trump has the authority to order Justice Department officials, those officials also have the right to quit rather than follow his direction.

“If the president is basically saying, ‘I want you guys to investigate yourselves, to convince me that you weren’t spying on me, there comes a point where DOJ has to say, ‘We’ll refer to the IG, but that’s all we’re doing,’ “ Vladeck said.

Trump’s demand came after a six-part morning tweetstorm in which he lashed out at Special Counsel Robert Mueller’s probe into his campaign, calling it “the World’s most expensive Witch Hunt”.

In the tweets, Trump accused the special counsel’s investigation of turning to other leads around the world after, in his words, finding no collusion with Russia or obstruction of justice in its ongoing probe.