“One of the focus points of the House Intelligence Committee's investigation is the U.S. government's response to actions taken by Russian intelligence agents during the presidential campaign,” said Representative Devin Nunes of California, the panel’s Republican chairman. “As such, the committee will make inquiries into whether the government was conducting surveillance activities on any political party’s campaign officials or surrogates, and we will continue to investigate this issue if the evidence warrants it.” Nunes’s counterpart atop the Senate Intelligence Committee, Richard Burr of North Carolina, was even more noncommittal. The committee, he said, “will follow the evidence where it leads, and we will continue to be guided by the intelligence and facts as we compile our findings.”

The statements were not the total brush-off that Democrats were hoping key Republicans would give to Trump, but they were indicative of a governing party that is growing more and more wary of the president’s tendency to pop off without facts, often in response to thinly-sourced news reports he sees in conservative media outlets. The White House made no attempt to substantiate Trump’s claim about Obama beyond the suggestion of counselor Kellyanne Conway, who on Monday noted that the president had access to intelligence that ordinary Americans did not. Whether that access had actually informed Trump’s allegation on Saturday was unclear; other reports said the president was merely re-circulating allegations that the conservative website Breitbart had picked up from Mark Levin, the talk radio host.

If Republicans reacted with the equivalent of an eye roll, Democrats saw something far more serious in the president’s latest tweetstorm.

“I think he crossed a line this weekend,” Representative Eric Swalwell of California, a member of the House Intelligence Committee, told me in a phone interview on Monday. “He lied to defame our former president.” Swalwell said that for Trump, it was part of “a pattern of deception and deflection when it comes to Russia.”

But the more concerning consequence, he said, was that the president’s comments could undermine confidence in the FISA system that allows the government to seek warrants from a special court to spy on those suspected of interacting with agents of a foreign power. “He’s the president of the United States, and he’s created a mess,” Swalwell said. “He’s taking a very strong country to its breaking point right now with his behavior.”

The top Democrat on the Intelligence Committee, Representative Adam Schiff of California, was more dismissive of the president’s call for an investigation into wiretaps, which came more than 24 hours after Trump fired off his initial tweets.

“It’s a nonsense request designed to cover up a nonsense tweet,” Schiff said in a phone interview Monday.“I don’t think anyone takes the president's tweets seriously anymore, and certainly not these.” He said it would actually be fairly simple for the committee to dig into Trump’s claim: All it had to do, Schiff said, was to call in James Clapper and ask the former director of national intelligence to repeat his denial, issued Sunday on Meet the Press, that the intelligence community had obtained a wiretap on Trump or his campaign.