The ranking Democrat on the House Intelligence Committee on Sunday said President Trump’s claims that former President Barack Obama Barack Hussein ObamaThe Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon Trump appointees stymie recommendations to boost minority voting: report Obama's first presidential memoir, 'A Promised Land,' set for November release MORE wiretapped Trump Tower are “patently false.”

“We are at the bottom. There is nothing at the bottom,” Rep. Adam Schiff Adam Bennett SchiffOvernight Defense: Top admiral says 'no condition' where US should conduct nuclear test 'at this time' | Intelligence chief says Congress will get some in-person election security briefings Overnight Defense: House to vote on military justice bill spurred by Vanessa Guillén death | Biden courts veterans after Trump's military controversies Intelligence chief says Congress will get some in-person election security briefings MORE (D-Calif.) told NBC’s “Meet the Press,” disputing a claim by Sen. Susan Collins Susan Margaret CollinsThe Hill's Campaign Report: Biden asks if public can trust vaccine from Trump ahead of Election Day | Oklahoma health officials raised red flags before Trump rally Gideon leads Collins by 12 points in Maine Senate race: poll Senate leaders quash talk of rank-and-file COVID-19 deal MORE (R-Maine) that lawmakers must get to the bottom of Trump’s claims.

Schiff said he expects FBI Director James Comey, who will testify Monday about the probe into Russia’s interference in the United States presidential election, will definitively put an end to Trump's allegations.

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Trump, without evidence, on March 4 accused Obama of wiretapping Trump Tower before the November election. Obama, through a spokesman, denied that he or any White House official ordered surveillance.

“What the president said was just patently false, and the wrecking ball it created now has banged into our British allies and our Germany allies,” Schiff said Sunday.

White House press secretary Sean Spicer last week accused the United Kingdom of aiding Obama in surveilling Trump Tower, reiterating a claim from a Fox News analyst. A spokesperson for Britain's GCHQ intelligence agency dismissed the allegation.

“It’s continuing to grow in terms of damage, and he needs to put an end to this,” Schiff added.