A mere four weeks ago The Day urged Congress to support the investigation by Special Counsel Robert Mueller III into possible collusion by the Trump campaign with the Russian government and possible obstruction of justice by the president himself.

Why does that need to be repeated so soon? Nothing has changed but so much has happened.

President Trump continues to fume that Mueller's investigation and his methods have gone too far, alarming some Senate Republicans to warn he would do harm to his presidency if Mueller were to be fired.

So concerned are some senators that a bipartisan group of four has resurrected provisions first proposed last summer and have offered a consolidated bill to keep Mueller's investigation from skidding to an end. The bill would write into law Department of Justice regulations providing that a special counsel can be fired only for good cause and by an existing Justice Department official. It calls for an expedited review of whether such a firing was for good cause.

The introduction of the bill by Republicans Thom Tillis of North Carolina and Lindsey Graham of South Carolina and Democrats Chris Coons of Delaware and Cory Booker of New Jersey was only one development in a whiplashing sequence of events this month. It followed an April 9 raid on the office and abodes of the president's personal lawyer, Michael Cohen, and a thus far unsuccessful effort by lawyers for Cohen and Trump to get a judge to allow them to review the seized materials before prosecutors did.

It preceded the revelation that Cohen's only other clients besides Trump since 2017 were the Fox News commentator Sean Hannity and a Republican party official seeking a discreet way to pay his mistress more than $1 million to get an abortion. It has culminated in the likelihood that President Trump is no longer willing to sit for an interview with the special counsel, given the fury he has expressed over the raid.

Momentum is building at a pace not seen since Watergate. The investigation has already led to five guilty pleas, including former campaign chairman Paul Manafort and former National Security Advisor Michael Flynn, and the sentencing of a Dutch lawyer. The effects of the pressure on the White House are reminiscent of the days of embattled President Richard Nixon.

Although other investigations, including Watergate, have taken two years or more to complete, Mueller may not have that kind of leeway. Not only he but also the deputy attorney general he reports to, Rod Rosenstein, may well be working on borrowed time. Reports that Trump would fire Rosenstein as a way to stop Mueller continue to surface.

Buying the investigation time would be the primary benefit of the bipartisan bill, but those in Congress who want to see a conclusive finding may have to seek another way. McConnell said Tuesday that he would not bring the bill to a floor vote, even if the Senate Judiciary Committee were to approve it. No doubt the majority leader perceives the bill's provisions as a threat to his power — hampering his ability to ignore the Justice Department rules or at least to drag out a review of "good cause" until the investigation trails grow cold. 

McConnell, himself a past target of the president's wrath, may also be blocking the bill because he sees little if any chance for it in the House. Stopping it now gives him the chance to flex his power.

Genuine leadership would be to use this bill as a way for Congress to assert its constitutional role to check and balance the executive branch. Maybe the president won't fire Mueller, as McConnell has opined. But Donald Trump is unpredictability personified. The nation can't live under the cloud of a half-finished investigation of such importance, and Congress could ensure that it does not have to.

The Day editorial board meets with political, business and community leaders to formulate editorial viewpoints. It is composed of President and Publisher Timothy Dwyer, Executive Editor Izaskun E. Larraneta, Owen Poole, copy editor, and Lisa McGinley, retired deputy managing editor. The board operates independently from The Day newsroom.