WASHINGTON (NYTIMES) - White House officials declared on Wednesday (March 8) that President Donald Trump was not the target of an investigation, five days after Trump himself raised the prospect with an unsubstantiated claim that his predecessor ordered the wiretapping of Trump Tower.

After first refusing to disavow Trump's allegations, made in a series of Twitter posts, and instead calling for Congress to investigate them, the press secretary, Sean Spicer, told reporters, "There is no reason that we have to think the president is the target of any investigation whatsoever."

Spicer's statement, which he read from a sheet of paper that was handed to him at the end of his briefing, reinforced the conundrum Trump's tweets have created for the White House: Either the president's assertions are baseless, or he may have implicated himself in a government investigation of contacts between his presidential campaign and Russia.

Until Wednesday, Spicer had steadfastly declined to discuss Trump's assertion that former President Barack Obama ordered wiretap surveillance of Trump Tower - an act that Trump condemned as a scandal comparable in scale to McCarthyism or Watergate.

Early into Wednesday's briefing, Spicer stuck to the policy he has followed since the storm broke over Trump's posts. Asked whether the president was the target of a counterintelligence inquiry, he replied: "I think that's what we need to find out. There's obviously a lot of concern."

But after an aide slipped Spicer a note, he circled back to clarify that "there is no reason to believe there is any type of investigation with respect to the Department of Justice."

The press secretary insisted he was not disavowing the president, who posted his tweets early on Saturday morning from Mar-a-Lago, his resort in Palm Beach, Florida.

"The tweet dealt with wiretaps," Spicer said. "The other is an investigation. They are two separate issues."

While the FBI is conducting a wide-ranging counterintelligence investigation into Russian interference with the 2016 presidential election, there is no public evidence that Trump is a target. The Justice Department defines "target" as someone whom investigators have substantial evidence against and who is likely to be indicted.

Current and former officials have said repeatedly that although they were concerned about intelligence suggesting meetings between associates of Trump and Russian officials, they have developed no evidence of collusion between Trump's campaign and Russia's hacking efforts.

Spicer cited the former director of national intelligence, James R. Clapper Jr., who last Sunday made that point on the NBC programme "Meet the Press."

But Clapper also said he had no knowledge the government had sought a warrant from a foreign intelligence court to install a wiretap in Trump Tower.

On Saturday, the director of the FBI, James B. Comey, asked the Justice Department to publicly reject Trump's claim that his agency had wiretapped his phones. The department has refused to do so.

Spicer complained bitterly about news media coverage of ties between Trump and Russia, saying it was fueled by leaks from anonymous sources, none of which had been substantiated.

"It's interesting how many times this fake narrative gets repeated over and over and over again," he said. "And yet no evidence has ever been suggested that shows the president has anything to do with any of the things that are being said. It's a recycled story, over and over and over again."

The problem for the White House is that Trump fuelled this week's cycle of stories himself. On Wednesday, the top Republican and Democrat on the Senate's Judiciary Subcommittee on Crime and Terrorism asked the FBI and the Justice Department for evidence that the government had sought legal permission to tap Trump's phones.

The request came in a letter from Sens. Lindsey Graham, R-S.C., and Sheldon Whitehouse, D-R.I., to Comey and the acting deputy attorney general, Dana Boente. Boente is overseeing the Russia inquiry because Attorney-General Jeff Sessions recused himself from any cases involving the Trump campaign and Russia, after acknowledging he met with Russia's ambassador, Sergey I. Kislyak.

"We request that the Department of Justice provide us copies of any warrant applications and court orders - redacted as necessary to protect intelligence sources and methods that may be compromised by disclosure, and to protect any ongoing investigations - related to wiretaps of President Trump, the Trump campaign or Trump Tower," the senators wrote.

With no evidence of wiretaps emerging, the White House has been forced into a defensive communications strategy. It has curtailed Trump's appearances before cameras, where reporters could ask him about his claims. Spicer held his briefing on Monday without TV cameras, though on Tuesday and Wednesday, he answered questions at length and before the cameras.

On Tuesday, the administration sent the secretary of homeland security, John F. Kelly, on CNN, where he, too, provided no evidence of any wiretapping.

However, Kelly said, "if the president of the United States said that, he's got his reasons to say it."