Washington (CNN) Six days after he accused his Oval Office predecessor of wiretapping him, President Donald Trump on Thursday again avoided questions about the charge, leaving his aides and allies still-struggling to explain his Saturday-morning broadside.

Trump was initially scheduled to come before cameras twice in the Roosevelt Room Thursday. Reporters saw him mid-morning speaking briefly with community bank CEOs, but he didn't address the wiretapping claims. A second photo-op with lawmakers to discuss the budget was scrapped last-minute, making for another 24 hours without further clarification from the commander-in-chief about his allegations.

That's left the charges hanging without any more details that could shed light on what Trump meant, or how he came by the information behind his claims -- which former intelligence officials deny and which have exasperated former President Barack Obama.

Investigation?

On Wednesday, Trump's press secretary Sean Spicer declared the White House had no reason to believe the President was under a counterintelligence investigation, which could have led to a warrant for wiretaps.

"There is no reason that we have to think the President is the target of any investigation whatsoever," Spicer said during his daily briefing, reading from a note handed to him by a deputy.

But Thursday, The New York Times first reported the Justice Department said Spicer hadn't consulted them before making his assertion. And according to standard agency procedure, they refused to comment on whether the FBI was undertaking a criminal investigation of Trump.

Spicer nonetheless stuck by his answer Thursday, insisting the White House wasn't aware of any probes into the President.

"We're not aware of anything," he said.

Capitol Hill

On Capitol Hill, lawmakers were pushing forward with their own investigation of Russia's interference in the 2016 presidential election, which -- at Trump's request -- will also include an inquest into the wiretapping claims.

Sources on the Senate Intelligence Committee said Thursday they want all potential Trump associates who allegedly spoke with Russian officials to testify before the panel as part of the investigation.

That includes Paul Manafort, Trump's former campaign manager who had lobbying ties to Russia; Michael Flynn, Trump's former national security adviser who was forced to resign after he misled administration officials about his conversations with the Russian ambassador; and Carter Page, a former adviser on the Trump campaign who also met with the Russian ambassador last year.

It's unclear when those Trump associates will come before the committee, but senators say they haven't ruled out the prospects of subpoenas if they don't comply.

Senators who have traveled to the Langley, Virginia, headquarters of the CIA said they have reviewed information about the extent of the aggressive Russian attacks meant to undermine the 2016 election. But the senators have not yet pieced together the information to determine any potential collusion between Trump allies and Russian officials.

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Tax returns

Sen. Dianne Feinstein, a California Democrat who sits on the intelligence committee, said she also wants to include Trump's tax returns -- which the President, bucking longstanding precedent, did not release during the campaign -- as part of this investigation.

"The tax returns become a primary lead into a Russia connection -- and that would be Russian money in his businesses," Feinstein told CNN. "He's visited Russia six times by his own voice on television. Who knows what the situation is?"

Feinstein said the committee was not yet prepared to issue subpoenas for Trump's tax returns, but that it was a "distinct possibility" in the future.

A Republican on the intelligence panel, Sen. Susan Collins, told CNN on Wednesday that it's possible the committee could try to obtain the returns, but that it was too early to take that step yet.

The committee rules allow Democrats to issue subpoenas without the consent of the GOP, but doing so could cause a partisan fight.

Silence

In the past week, Trump himself has remained entirely silent on the swirl of Russia questions. He last took questions from reporters during a tour of the USS Gerald Ford in Newport News, Virginia, when he responded briefly to queries about Attorney General Jeff Sessions' meetings with the Russian ambassador.

After he launched his explosive Twitter accusations on Saturday morning, he's kept largely out of sight. Instead of the usual parade of photo-ops in the West Wing this week, Trump has remained mostly behind closed doors and away from reporters eager to inquire about his claims.

Monday was the first weekday of Trump's presidency without a press availability or speech. On Tuesday, a meeting with AFL-CIO President Richard Trumka was abruptly closed to cameras, even as reporters lingered outside the Oval Office prepared to ask Trump about the wiretapping claims. On Wednesday Trump retreated again, selling Obamacare to conservatives away from the press.

He emerged again on Thursday during a meeting with CEOs of community banks, but didn't diverge from his prepared remarks hailing a recent executive order he said will allow the banks to issue loans at a quicker pace.

And when it came time for reporters to file into his lunch with Republican lawmakers, the announcement came down: The photo-op was canceled.