"At least we have something in common, perhaps", Trump quipped during a joint news conference with Merkel.
Merkel, who was making her first visit to the White House since Trump took office, looked surprised by the president's comment, which he appeared primed to deliver.
Asked how he concluded he was being snooped on, Trump cited a January 20 New York Times article 'where they were talking about wiretapping.
Republican Rep. Charlie Dent of Pennsylvania said there is no evidence or proof of Trump's claim and "he should simply retract it and move on". And if you are, then clearly the president was wrong. Graham has previously said he would use subpoena power to get information from the Federal Bureau of Investigation about whether a warrant was issued allowing the Obama administration to tap Trump's phones during the campaign.
"And I don't believe, having spoken to people just in the last week, I don't believe there was an actual tap of Trump Tower".
"They are utterly ridiculous and should be ignored", read the statement, which was issued on condition that it be attributed to an anonymous spokesperson to protect the identity of agency staff.
The early morning tweets he sent out from his Mar-a-Lago estate in Palm Beach, Florida on March 4 now threaten to derail the White House's wider agenda and have sparked a spat with close ally Britain.
Spicer all but screamed at Jonathan Karl, ABC News' chief White House correspondent, demanding, "Where was your passion and where was your concern when they all said that there was no connection to Russian Federation?"
"He stands by it", Spicer insisted in his Thursday briefing. He said reporters have not focused enough on comments from officials denying evidence of any collusion between Russian Federation and the Trump campaign. It's unbelievable what you can get done when you listen to what the other side wants, he would always remind me.
We are about to enter the big "health care" debate of 2017.
In a rare public statement, Britain's GCHQ, Britain's Government Communications Headquarters, the equivalent of the US National Security Agency which monitors overseas electronic communications, said the claims were "nonsense" and should be ignored. "There is a ton of media reports out there that indicate that something was going on during the 2016 election", Spicer said.
Slack pointed out that GCHQ could not have spied on Trump because the United Kingdom and the USA are both members of the Five Eyes intelligence-sharing alliance, and under "the Five Eyes pact, we cannot use each other's capabilities to circumvent laws".
In other words, Democrats want their leadership to work as much as possible with the new administration.
The diplomat and White House official both spoke only on condition of anonymity to discuss private conversations.
US President Donald Trump has a credibility problem - with some of his fellow Republicans in Congress and in his cabinet - because of his habit of throwing things out there and leaving it for them to clean up his mess.
On March 4, Trump sparked a furor with tweets that accused former President Barack Obama of ordering a wiretap on the NY skyscraper, where Trump and his family live and run his real estate empire.
Graham says he has seen no evidence to support Trump's claim that the Obama administration wiretapped him previous year. The department would not comment further on what information, if any, was provided.