John McCain
John McCainReuters

Republican Senator John McCain (R-AZ) on Sunday urged President Donald Trump to come up with evidence proving that former President Barack Obama wiretapped that the phones at Trump Tower or retract his claim.

“I think the president has one of two choices: either retract or to provide the information that the American people deserve, because, if his predecessor violated the law, President Obama violated the law, we have got a serious issue here, to say the least,” McCain said, according to The Associated Press.

Trump asserted in a tweet last week, “Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory. Nothing found. This is McCarthyism!” He continued the allegation against Obama in other tweets but offered no evidence.

Last week, several senators asked the FBI and the Department of Justice for any information they may have about Trump's claim of wiretapping.

The House intelligence committee has said it would look into Trump’s claims of wiretapping as part of an existing investigation of Russia’s role in the 2016 presidential campaign.

Obama’s director of national intelligence, James Clapper, has said that nothing matching Trump’s claims had taken place, but that has not quelled speculation that Trump’s communications were monitored by the Obama administration.

Trump has asked Congress to investigate.