The initial shock had largely worn off, the expressions of dismay and disappointment and the calls for his resignation were all on the public record and Sen. Bob Menendez went about his normal routine in the halls of Congress while his team of attorneys worked on constructing a defense against the bribery charges lodged against him and his wife by federal prosecutors.

Then, the second shoe dropped — a stunning superseding indictment accusing Menendez of using his office to advance the interests and agenda of the Egyptian government –- a violation of Federal law — to enrich himself.

The implications are unimaginable: a sitting U. S. Senator, chairman of the influential and powerful Senate Foreign Relations Committee with access to highly sensitive and classified government documents allegedly doing the bidding of a foreign government.

The indictment does not allege espionage, but rather that the Senator, his wife Nadine and an Egyptian businessman ”willfully and knowingly coordinated, conspired, confederated and agreed together and with each other to have a public official (Menendez) act as an agent of a foreign principal — the government of Egypt and Egyptian officials.”

They stand accused of failing to register as   agents of a foreign government, although Menendez, as a government official, is already prohibited from engaging in such activity.

While there is a significant difference between  allegations of espionage and failure to comply with a registration requirement — a bureaucratic task —  doing favors for and sharing government information with a foreign power will likely be construed by many as a distinction without a difference.

As is usually the case, a complex set of circumstances will be broken down to a simple allegation: Menendez, as a U. S. Senator, placed the interests of Egypt over the interests and well-being of the United States, the nation whose safety and security was entrusted to him by his Constitutional oath.

It is a devastating accusation, one not brought lightly by prosecutors against a member of the United States Senate.  They were certainly aware of the reaction such an indictment would evoke but seemingly are confident their evidence is sufficiently solid to prevail at trial.

Menendez, as he did when the conspiracy to commit bribery indictment was brought in late September, denied any wrongdoing and attributed the indictments to forces arrayed against him engaging in a smear campaign.

It’s not precisely former President Trump’s “witch hunt” defense, but it’s close.

The Senator has rebuffed all demands for his resignation while leaving open a re-election campaign — even in a contested primary — seemingly convinced he remains powerful enough  to withstand an onslaught from within his own party and, should he secure renomination, from a Republican opponent in 2024.

Should he remain rigidly defiant — and there is no indication he will not — the Democratic leadership will suffer a political migraine of epic proportions.

He’s lost the support of the establishment from Gov. Phil Murphy through most of the Democratic Congressional delegation and county chairs and more than half his colleagues in the Senate.

The latest foreign agent indictment may turn out to be the last straw for his Senate colleagues.

Murmurs of expulsion can be heard, even though Senate Majority Leader Charles Schumer has remained silent, refusing to call on Menendez to resign, and the White House only response thus far is a ho hum characterization of the indictments as “a serious matter.”

It is likely that private back channel conversations have occurred between Menendez and national Democrats — perhaps even from the Biden Administration — to gauge the possibility of persuading the Senator to step down.  If so, they’ve all come to naught.

Realistically, New Jersey’s establishment, has little leverage to force a resignation if Menendez continues to assert his innocence and remains in office.

A successful primary challenge is the sole alternative, a coalescing behind a challenger and throwing the party’s organizational and financial resources into the race.

While Third District Congressman Andy Kim is the only announced challenger at this point, others have displayed some interest.  A multi-candidate field, however, would go against the party’s best interest, potentially splintering the vote and creating a lane for Menendez to win with a small percentage.

Murphy and the leadership face the daunting — but crucial — task of uniting the party or risk an outcome that in a contest of wills Menendez will emerge as bigger than the party itself.

They must bear in mind that, according to the tentative trial date schedule, the primary campaign will be in full throttle while testimony — some of it potentially damaging — will dominate media coverage.

Menendez is in the battle of his life to salvage his career and reputation and potentially avoid prison.  The forces arrayed against him are formidable and armed with unlimited resources.

He may be caught in a typical Capitol Hill reaction to those accused of major transgressions – when the accused is encountered, avoid eye contact and move to the opposite side of the corridor to pass by.

This is not another internal political brawl at the county or state level — the kind Menendez and his dedicated allies normally win — but a titanic struggle to the last soldier standing.

Carl Golden is a senior contributing analyst with the William J. Hughes Cener for Public Policy at Stockton University.