Republicans in Congress say they expect to see ‘smoking gun’ evidence that definitively corroborates President Donald Trump’s claim that the Obama administration spied on his transition team after the election, according to Fox News.

GOP lawmakers on the House Intelligence Committee anticipate that classified information that was supposedly seen by Chairman Devin Nunes, the California Republican, will show that intelligence was collected on members of the Trump transition, anonymous sources told Fox News.

The sources said that the intelligence was known to Nunes even before Trump fired off his tweets on the morning of March 4, in which he accused his predecessor, Barack Obama, of tapping his phones.

This new information is ‘said to leave no doubt’ that the Obama administration had used surveillance on foreigners as a legitimate cover to spy on then-President-elect Trump.

GOP lawmakers on the House Intelligence Committee anticipate that classified information that was supposedly seen by Chairman Devin Nunes (above), the California Republican, will show that intelligence was collected on members of the Trump transition

The sources say that members of the Trump transition team were ‘unmasked’ – or had their names revealed in intelligence reports.

The purpose of such unmasking was to damage the incoming Trump administration, according to Fox News.

While the FBI has not responded to the committee’s request for documents, the National Security Agency is likely to provide evidence to the panel on Friday, Fox News reported.

On Wednesday, Nunes dropped a bombshell when he told reporters on Wednesday that the US intelligence community collected ‘incidental’ information about Trump and his transition team during the three-month transition.

Nunes told reporters on Capitol Hill that the information collected was 'legally collected' pursuant to a warrant issued by a FISA judge in a federal court, and concerned 'foreign' surveillance - before he went to the White House to tell the president.

Sources also told Fox News that the ranking Democrat on the House Intelligence Committee, Adam Schiff, has seen the classified material that Nunes was referring to on Wednesday

He said 'it's possible' that the now-president's personal communications were among those which were part of the 'incidental' collection - but did not say definitively if that was the case.

But that 'did not involve Russia or any discussions with Russians,' Nunes said, adding that he was 'alarmed' to learn what he did.

Lawmakers expect that the NSA’s files will go even further than Nunes’ claims, with one source telling Fox News that the agency may produce a ‘smoking gun’ that will definitively establish that there was espionage committed by the Obama administration.

Sources also told Fox News that the ranking Democrat on the House Intelligence Committee, Adam Schiff, has seen the classified material that Nunes was referring to on Wednesday.

Nunes, meanwhile, apologized to Democrats on the committee on Thursday, according to CNN.

His news conferences and his decision to brief Trump at the White House on the purported revelations angered Democrats who said that it taints the committee’s standing as an impartial body tasked with investigating Trump’s alleged ties to Russia.

Trump, meanwhile, remarked that after meeting Nunes he felt ‘somewhat’ vindicated by his claims – thus far unsupported by evidence – that Obama spied on him.

FBI Director James Comey testified before the committee on Monday that the bureau is investigating possible ties between the Trump campaign and the Russian government.

Schiff made headlines of his own on Wednesday, telling MSNBC that the evidence linking Trump’s team to the Kremlin was ‘more than circumstantial,’ though he would not offer specifics.

Schiff’s remarks seem to echo a CNN report which quoted anonymous government officials as saying that the evidence currently in the hands of the FBI suggests that the Trump team colluded with Moscow in the dissemination of material damaging to Hillary Clinton during the recent campaign.