Nixon resigns the presidency after it became clear he had obstructed justice in the Watergate case. Photo: Dirck Halstead/Getty Images

As we await the release of the Mueller report, an open question is whether evidence of serious presidential misconduct (even if it doesn’t, as Attorney General Barr’s “summary of principal findings” has asserted, rise to the level of any indictable offense) — will have any major impact on Donald Trump’s so-far impressive Republican support in fighting what he calls a “witch hunt.” The obvious precedent for believing that such a finding would erode his position even among Republicans is what happened to Richard M. Nixon in August of 1974, when the so-called “smoking gun” tapes were released (by order of the U.S. Supreme Court) showing him and his staff very clearly talking about suppressing any Watergate probe, well before the 1972 presidential election. As Politico noted on the 44th anniversary of this event, Nixon’s position deteriorated rapidly:

Nixon’s remaining political support on Capitol Hill all but disappeared. The 10 Republican members of the Judiciary Committee who had voted against impeachment in committee announced that they would now vote for impeachment once the matter reached the House floor. Nixon lacked support in the Senate as well. Sens. Barry Goldwater (R-Ariz.) and Hugh Scott (R-Pa.), the minority leader, told Nixon that no more than 15 senators were willing to even consider an acquittal. Facing impeachment by the House and near-certain conviction in the Senate, Nixon announced his resignation on the evening of Aug. 8, 1974, effective as of noon on the following day.

Is this sort of “ka-boom!” possible with respect to Trump? Probably not, unless the full Mueller report contains something unexpectedly shocking. If if does, there’d be some Republican heartburn, wouldn’t you think?

Yes, there could be some leakage of Republican support, or more likely louder squawking from the handful of Republicans who have resisted surrendering to the president’s blandishments and threats. But there are five reasons a broader Republican backlash like the one that helped push Nixon out of office won’t happen, even if it turns out Mueller’s report suggests obstruction of justice may have occurred after all (a possibility raised by Mueller’s conclusion that the evidence neither proved criminal obstruction beyond a reasonable doubt, nor exonerated Trump).

1. Trump and his defenders are arguing there’s no underlying crime. Nobody could say that with respect to Watergate. The endlessly repeated Nixon defense was that he knew nothing about the “third-rate burglary” of Watergate until long, long after the event. The smoking-gun tapes showed Nixon and his chief of staff talking about how to hush it all up a month after it occurred. Even a “third-rate” burglary is a felony. As Matthew Walther notes, that makes a difference:

[A]bsent any evidence of actual collusion between Trump and the Kremlin, it is difficult to imagine rank-and-file Republicans, to say nothing of the party’s leadership, thinking there is anything wrong with obstructing a long-winded investigation of non-crimes.

This is the heart of the “witch hunt” argument, and it takes Republicans into the same territory successfully defended by Democrats when Bill Clinton was impeached in 1998 (when obstruction of justice was one of the articles of impeachment): Clinton was refusing to cooperate with an investigation of matters that shouldn’t have been investigated in the first place. That is exactly what we are hearing from most Republicans now with respect to the Mueller investigation, and before that, the FBI’s investigation of alleged collusion with Russia. It’s an illegitimate investigation, so who cares if the president tried to stop or curtail it?

There is a parallel argument made by some Republicans that presidents cannot commit “obstruction of justice” if the alleged misconduct is nonetheless within the scope of executive powers that are constitutionally sanctioned. No one in Nixon’s days had yet thought of that extension of the imperial presidency he otherwise exemplified.

2. Nixon was a lame-duck president; Trump’s definitely not. When the buzzards began circling Richard Nixon’s presidency, he was well into his second term, and faced a Democratic-controlled Congress that was not about to let him off the hook for any Watergate-related revelations. By the time definitive evidence of obstruction of justice emerged, the House was already considering articles of impeachment, and Democrats held 56 Senate seats. Trump is already running for reelection in what bids fair to become a savagely polarized 2020 campaign, and his party controls the Senate and thus can make (and almost certainly already has made) his removal from office via the impeachment process all but impossible. To the extent that Trump’s entire presidency is the product of some of the most intense partisanship in living memory, and his entire personality is based on his identity as a “winner,” the odds of him ever resigning in the face of attacks from Democrats seem very low. And Republicans know that.

3. Trump is a lot more popular among today’s Republicans than Nixon was among yesterday’s. People remember that Richard Nixon was reelected in 1972 by a huge landslide, but was forced to resign less than two years later. But it’s less clearly remembered that in between the two events his popularity steadily dropped — among Republicans as well as Democrats and independents.

According to Gallup, Nixon’s job-approval ratings among Republicans fell from 91 percent in February of 1973 to 54 percent by October of that year. There were multiple reasons for that plunge, including, yes, Watergate publicity (punctuated by the Saturday Night Massacre in which Nixon fired his attorney general, his deputy attorney general, and the Watergate special prosecutor), plus the resignation of his vice-president, Spiro Agnew, after being caught accepting bribes; growing public hostility to delays in ending the Vietnam War; and the beginning of a recession that interrupted a long period of economic growth. By the time Nixon was forced to resign, his approval rating overall was a terrible 24 percent, and just 50 percent among Republicans.

At present, Trump’s approval rating among Republicans (also according to Gallup) is at 89 percent. It’s never been lower than 79 percent during his presidency. As long as he’s this popular among his party’s rank and file, he’s got a decent shot at reelection, and more to the point, few in the ranks of GOP elected officials are going to cross him.

4. The Republican Party is more monochromatic ideologically than it was during Watergate. Many conservative Republicans defended Nixon long after the public had soured on him. That gave him some Republican support, but in those days of a strong moderate and even liberal wing of the GOP, it wasn’t enough to save him, as I noted in an earlier piece on the relative durability of Trump’s support:

While we tend to look back at Watergate and perceive a gradual national consensus over Nixon’s criminality, it came slowly to conservative Republicans, right up to and sometimes beyond the release of the “smoking gun” tape that proved Nixon’s complicity in the Watergate cover-up, which he had repeatedly denied. In the end only a minority of Republicans (mostly moderate-to-liberal Republicans) on the House Judiciary Committee voted for articles of impeachment, and soon the GOP was embroiled in a presidential nominating contest between the man (Reagan) who defended Nixon to the last ditch and the man (Ford) who pardoned him.

It’s generally forgotten that in 1974 the U.S. Senate included a wide variety of moderate-to-liberal Republicans such as Lowell Weicker, Charles Percy, James Pearson, Charles Mathias, and many others. Now that species of Republican is long gone, and even those considered “moderates” are more accurately moderate conservatives. That means any Republican president of the United States is going to have more monolithic support from GOP elected officials, particularly when said president is especially popular among rank-and-file conservatives.

Anyone who watched the performance of Republicans on the House Oversight Committee during the testimony of former Trump attorney Michael Cohen (with the sole exception of libertarian heretic Justin Amash) recognized a savagely pro-Trump posture that did not comport with any interest in the underlying facts. These lawmakers are reminiscent of no one in the Watergate saga more than Representative Earl Landgrebe of Indiana, who famously said soon before Nixon resigned: “Don’t confuse me with facts; my mind is made up … [I’ll] stick with my president even if he and I have to be taken out of this building and shot.”

5. Trump’s whole approach to politics incentivizes partisan combat, not fact-based investigations. Whether or not Donald Trump is a symptom of partisan and ideological polarization on the right, or its cause (he’s almost certainly both), we have long passed the point at which Republicans are particularly concerned about whether his words are truthful or his behavior is lawful. If we’ve all become somewhat desensitized to presidential lying, it’s particularly true of fellow partisans whose daily bread is Fox & Friends, and who glory in how crazy his lies drive journalists and Democrats. Those who can remain calm when their president makes up a myth of “millions of illegal votes” for his opponent in 2016 because he can’t accept the fact that he lost the popular vote, and routinely threatens his enemies with extra-constitutional vengeance, are not suddenly going to dump him just because Robert Mueller concludes he probably had malign motives for firing James Comey. It would seem crazy to the “party base” to treat as intolerable the sort of unsavory but noncriminal allegations we are likely to hear, when Republicans have already tolerated — indeed, celebrated — so much else. Indeed, even before the Mueller report’s release, key congressional Republicans are announcing it’s harmless, sight unseen.

Now, of course, it’s always possible that Mueller or House Democrats will now or later produce evidence of something even worse than we imagined that just happens not to involve collusion with Russia or obstruction of justice. Then, perhaps, we’d find out that Trump exaggerated in his chilling boast that he could “stand in the middle of Fifth Avenue and shoot somebody” and not lose voters. But anyone who counts on Republicans to take him down, or roll over as many of them did with Nixon, hasn’t really been paying attention.