GOP Rep. Justin Amash Justin AmashOn The Trail: How Nancy Pelosi could improbably become president History is on Edward Snowden's side: Now it's time to give him a full pardon Trump says he's considering Snowden pardon MORE (Mich.) on Saturday called on President Trump to release information backing up his allegation that former President Barack Obama Barack Hussein ObamaGOP senator blocks Schumer resolution aimed at Biden probe as tensions run high D-Day for Trump: September 29 Obama says making a voting plan is part of 'how to quarantine successfully' MORE had wiretapped Trump Tower during the campaign.

"This allegation has serious implications. @POTUS should provide more info to Congress immediately to assess constitutionality and legality," wrote Amash, a frequent Trump critic.

This allegation has serious implications. @POTUS should provide more info to Congress immediately to assess constitutionality and legality. https://t.co/AuIrhKJMcc — Justin Amash (@justinamash) March 4, 2017

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Amash's tweet echoed remarks from two other Republicans on Saturday, Sens. Ben Sasse (Neb.) and Lindsey Graham Lindsey Olin GrahamSenate Republicans signal openness to working with Biden Loeffler calls for hearing in wake of Netflix's 'Cuties' Quinnipiac poll shows Graham, Harrison tied in South Carolina Senate race MORE (S.C.), who indicated they were pushing for more information.

Graham said he was "very worried" about Trump's claim that Obama ordered a wiretap of Trump Tower before the November election. He said an illegal wiretap would represent "the biggest political scandal since Watergate," while the ability of the Obama administration to legally obtain a warrant would also be a scandal.

Trump on Saturday claimed Obama had his “wires tapped” in Trump Tower before Election Day, tweeting the accusation without offering evidence.

“Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory. Nothing found. This is McCarthyism!” Trump wrote, adding in another that Obama was "turned down by court earlier."

Sasse noted that such a wiretapping warrant would have been approved by a court under the Foreign Intelligence Surveillance Act (FISA).

According to a senior White House official cited by The New York Times, Trump's chief counsel Don McGahn was working on Saturday to secure access to what he believed to be an order issued by the FISA court involving surveillance related to Trump or associates.

The Times reported that the official didn't offer evidence supporting the idea that such an order exists, but noted that it would be "highly unusual" for the White House to order the Department of Justice to turn over such an order given a tradition of independence for law enforcement.