Hoo boy. Only two possible explanations for this that I can see, and they’re both bad for Dems. (And not mutually exclusive.)

1. Team Schumer is showing rank favoritism towards Chuck’s tri-state buddy Menendez, prioritizing his reelection above that of Democratic incumbents like McCaskill and Tester and Donnelly who are under severe threat in red states.

2. Team Schumer is performing triage, writing off McCaskill and Tester and Donnelly — and the Democrats’ hope of a Senate majority — as electorally dead and focusing instead on saving blue states that were supposed to be safe but maybe aren’t.

Bad day for liberals either way:

The Senate Democrats’ leading super PAC is set to spend $3 million in bright blue New Jersey in an effort to save Sen. Bob Menendez, who has struggled to put away a Republican challenger after facing a corruption trial last year.

Senate Majority PAC, which is controlled by allies of Senate Minority Leader Chuck Schumer (D-N.Y.), will use the cash to air a statewide ad attacking Menendez’s opponent, former pharmaceutical executive Bob Hugin, as an ally of President Donald Trump in a state where the president is deeply unpopular…

Menendez, who is running for his third term in the Senate and is the top Democrat on the Senate Foreign Relations Committee, leads in most recent public polling of the contest. But Democrats fear his lead isn’t big enough in the face of the millions that Hugin has spent and will keep spending on the airwaves out of his personal fortune. Hugin and his allies have swamped Democratic spending in the race by roughly a 7-to-1 margin, $21.8 million to $3.3 million, according to a source that tracks media buys.

I’m intrigued that the Schumer brain trust is this worried about Menendez after the last two polls of the state had him leading by 10 and 11 points, respectively. Hugin might make Dems sweat there but Menendez will probably hold on. In the meantime, the three Dems I mentioned above are all either narrowly ahead or within the margin of error in their own races. Why wouldn’t the PAC prefer to gamble on them instead of on Menendez? You’d get much more bang for your ad buck in Montana, especially, than in Jersey.

All of which is a long way of asking if Schumer knows something about the trends in those states that we don’t. Even if McCaskill etc look dead in the water, surely Bill Nelson and Kyrsten Sinema still stand a solid chance of winning. Why not spend on them instead?

If in fact Democrats end up losing a bunch of races narrowly, their decision to renominate sleazy Bob Menendez instead of a fresh candidate with less baggage could be an underreported but potentially significant factor. Every dollar that Schumer and others are throwing at Jersey to prop him up is a dollar not going to a more competitive race. Presumably Democrats figured that even a weak incumbent like Menendez would have little difficulty in a deep blue state against token Republican opposition; problem is, they didn’t get a token. In Hugin they got a guy willing to bury them in spending in hopes of stealing the seat. Hugin may end up an unsung hero of Election Night by forcing Democrats to defend what should have been an unbreachable fortress, drawing resources away from more winnable states.

But wait, it gets worse:

Yep, that’s correct. When the feds came after Menendez and his buddy Salomon Melgen for bribery, they flagged $600,000 that Melgen had donated to a Democratic group as part of the quid pro quo on Melgen’s end. That group? The Senate Majority PAC, of course. What a sweet deal for Menendez: Not only was his party willing to overlook all that courtroom unpleasantness and offer him another term in the Senate but the PAC his crooked friend Sal “invested” in is now repaying Menendez with a fivefold expenditure to his reelection campaign. Thank goodness Democrats are coming to drain the swamp from Trump.

Oh, and just to put a bow on this: Kerpen also notes that the ad the Senate Majority PAC is running for Menendez slams Bob Hugin for making out like a bandit on drug prices with federal help. Melgen, meanwhile, was sentenced to 17 years in prison earlier this year for “stealing $73 million from Medicare by persuading elderly patients to undergo excruciating tests and treatments they didn’t need for diseases they didn’t have.” Is the PAC’s problem with Hugin that he’s not quite ruthless enough in manipulating the system to squeeze money out of sick people? Hugin should try offering them a check to take the ad down. Evidently they’ll cash one from anyone.

Update: Kerpen offers a third possibility to explain the $3 million Jersey expenditure:

That would let Team Schumer off the hook for terrible political judgment but it sure wouldn’t let the donor off. Who’s so enamored of Bob Menendez that they’d throw three mil at his race instead of spreading the money around nationally? It’s the Democrats’ Beto problem all over again, piling cash on a candidate who needs it less urgently than others do.