It is good to see that some of our political leaders in Washington will not entertain giving President Donald Trump a pass on his stunning allegations made a week ago that his predecessor, President Barack Obama, committed a criminal act by ordering electronic surveillance of communications from Trump Tower prior to the election.

Since Trump has not repeated the claims in the week since, it appears he would just as soon move on. Instead, Congress must find the underlying facts behind this tall tale.

The most likely explanation is that the sitting president, after reading some wild right-wing speculative commentary, issued his series of tweets in an effort to divert attention from continuing questions about communications between people associated with the Trump campaign and Russian officials.

If that is the case, the recklessness of the act is stunning. A president, with the power to get the information about any surveillance carried out by federal intelligence agencies, chooses to accuse a former president of felonious behavior without checking the facts.

The series of tweets again raises serious questions about the capacity of Trump to serve as president.

“How low has President Obama gone to tapp (sic) my phones during the very sacred election process,” stated Trump in one of a series of tweets last Saturday. And just to make sure no one would consider these lawful surveillances, he added: “This is Nixon/Watergate.”

An earlier tweet had characterized the alleged behavior as “McCarthyism!”

“Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory,” Trump wrote in the tweet.

If those allegations are untrue, as is highly likely, the damage cannot be undone. Legions of Trump supporters will remain convinced that Obama ordered the wiretapping of Trump phones, no matter what the facts ultimately show. The result is further erosion of confidence in our governmental institutions.

Two senators last week called Trump’s bluff. Sen. Lindsey Graham, R-S.C. and Sen. Sheldon Whitehouse, D-R.I., wrote to James Comey, director of the FBI, and Acting Deputy Attorney General Dana Boente requesting, “Copies of any warrant applications and court orders … related to wiretaps of President Trump, the Trump campaign, or Trump tower.”

Graham said if the Justice Department does not cooperate, the senators are prepared to subpoena the documents.

The expectation is that no warrant applications or judicial orders will be turned over because none exist. If wire taps were authorized, it means a judge concluded there was good reason to suspect criminal acts would be uncovered by the surveillance. That’s hardly good news for Trump.

In the wake of the scandal that drove President Richard Nixon from office, U.S. laws were passed to prevent a president from directly ordering clandestine surveillance. Instead, federal intelligence authorities must ask a judge to authorize the action, providing proof of likely criminal behavior.

Trump has offered no proof that Obama, in what would be a conspiracy at the highest levels, ignored the law and directly ordered surveillance of Trump and others in his campaign. It is a fantastical notion, one no rational political leader would make without proof. Yet that is almost certainly what Trump has done.

What is the penalty if it turns out Trump smeared a former president without evidence? Only Republicans, in control of the House and Senate, can answer that question. At the very least, an official rebuke by the Congress would be in order.

If the Republican Congress does not show the guts to draw lines for this president, it invites a constitutional or other crisis to come. Graham, by joining Whitehouse, showed he will not turn a blind eye.