He said that at this point, the only crime for which there has been clear evidence is the leaking of classified information - namely, Flynn's name - and the Intelligence Committee will continue to investigate that. He drew parallels to Watergate and McCarthyism and said Obama was a "Bad (or sick) guy!" for ordering surveillance of his NY residence - allegations the former president quickly denied through a spokesman.
Nunes said Monday's hearing would also look into the possibly illegal leaking of national security information since Trump's election in November.
Trump on March 4 tweeted that Obama had "tapped" his phone - a charge that has consumed political debate in the U.S. capital.
FBI Director James Comey will testify before the House Intelligence Committee Monday where he could debunk Trump's wiretapping claims as well as allegations that the Trump campaign worked with the Russians to interfere in the U.S. election.
Nunes stressed Sunday that he also hasn't seen evidence that the Trump campaign collaborated with the Kremlin and wanted the focus placed on leaks from the intelligence community.
"We have to understand everything about the ties between Russian Federation, the Trump campaign, the Trump transition, the Trump administration", said Kaine, a member of the Foreign Relations Committee and Democratic presidential candidate Hillary Clinton's running mate.
On Monday, the House Intelligence Committee will hold a hearing, which will include testimony from Federal Bureau of Investigation director James Comey. Grassley had threatened to hold up Trump's nominee for deputy attorney general, Rod Rosenstein, until Comey briefed them. "So if you take the President literally, it didn't happen", Nunes said.
The FBI is also probing Russian interference in the election.
Despite a rising number of officials who say there is no evidence, Trump and aides have not backed down from the Obama wiretapping claim.
Based on "everything I have up to this morning - no evidence of collusion", said US Representative Devin Nunes, head of the House Intelligence Committee, speaking to the Fox News Sunday television program.
White House efforts to support the claims ended up embroiling two key European allies: Britain and Germany.
"The President doesn't go and physically wiretap something". Obama, through a spokesman, denied that he or any White House official ordered surveillance. "I think the concern that we have is that, were there any other surveillance activities that were used". Germany's Chancellor Angela Merkel, whose phone was once tapped by USA intelligence, did not take kindly to Trump's quip that they had something in common Friday.
The apparent lack of evidence for Trump's claims is causing consternation among the President's Republican allies and Democrats alike, and speculation about how he will respond if Comey testifies that they are baseless.
The issue of wiretapping first surfaced last month, when Trump's national security adviser Michael Flynn was forced to resign after it was revealed he had misled top officials over his contacts with the Russian ambassador to Washington to discuss sanctions Obama had just announced against Russia over the election hacking. "We do know that the Obama administration targeted their political enemies.so the notion is not necessarily outlandish, but it's serious", he said. "Now I don't want to prejudge where we ultimately end up".