Barack Obama’s nominee to replace Justice Scalia on the Supreme Court cannot be confirmed by the U.S. Senate without the co-operation of Republicans, because there are 54 Republicans in the Senate. That’s enough to block Democrats from getting (1) the 50 votes needed to confirm (the tiebreaking 51st would be Vice President Biden), (2) the 60 votes needed to break a filibuster, or (3) the 50 votes needed (plus Biden) to change the Senate rules to eliminate the filibuster. Of course, if Hillary Clinton wins the presidential election, the nomination could be sent back and the GOP would likely have to confirm someone acceptable to her. But otherwise, while they can use Senate procedure to make it painful for Republicans to hold the line, it looks like the Democrats would have no recourse if Republicans win in November, thus setting up the presidential election as the closest thing we have had in memory to a direct referendum on the Supreme Court.

Judging by this NBC News report by Ari Melber, some Democrats are now floating a novel idea: that if they lose the presidential election but recapture the Senate, they could vote down the filibuster rule and ram through a nominee in the 17-day interregnum between when the new Senate is seated January 3 and when the new President is inaugurated (and the nomination rescinded) on January 20.

Let’s unpack the problems with this scenario.

Problem 1: Coattails It’s really hard to win back the Senate without also winning the presidential race. Yes, there have been years like 2000, when Democrats gained four Senate seats while losing nationally. But 2000 was really unusual (Gore, as you’ll recall, won the national popular vote). Let’s look at the six states where Democrats picked up seats in 2000, measured by the Democrats’ two-party presidential vote in those states in 1996 and 2000 (five of these six had Republican incumbents; Florida was an open seat):

Delaware: 58.6% in 1996, 56.7% in 2000
Washington: 57.2% in 1996, 52.9% in 2000
Michigan: 57.3% in 1996, 52.6% in 2000
Minnesota: 59.4% in 1996, 51.3% in 2000
Florida: 53.2% in 1996, 50.0% in 2000
Missouri: 53.6% in 1996, 48.3% in 2000

And then there’s the two states where Republicans had Senate pickups, again by the Democrats’ share of the two-party vote:

Nevada 50.6% in 1996, 48.1% in 2000
Virginia 48.9% in 1996, 45.9% in 2000

In other worse, aside from Florida (which was famously 50/50 that year), Democrats picked up a Senate seat in only one state Gore lost, and their pickups included two states where Clinton had carried 52-54% of the two-party vote four years earlier, and four where he carried 57-60%. This was a very bad map for Republicans.

Now let’s look at the 2016 Senate races, and you will see that while the GOP has a lot of headaches to defend, it will be hard for Democrats to match 2000 without winning the national election. Here’s the GOP Senate seats up this year in states where the Democrats won at least 44% of the two-party presdential vote in 2012:

Illinois (Kirk) 58.6%
Wisconsin (Johnson) 53.5%
Iowa (Grassley) 53.0%
New Hampshire (Ayotte) 52.8%
Pennsylvania (Toomey) 52.7%
Ohio (Portman) 51.5%
Florida (open – Rubio) 50.4%
North Carolina (Burr) 49.0%
Georgia (Isakson) 46.0%
Arizona (McCain) 45.4%
Missouri (Blunt) 45.2%
Indiana (open – Coats) 44.8%
South Carolina (Scott) 44.7%

Two Democratic seats are also up in states where the GOP was competitive but unsuccessful in 2012:

Nevada (open- Reid) 53.4%
Colorado (Bennet) 52.8%

That’s a map with a lot of opportunities for Democrats and peril for Republicans, but unlike 2000, there’s only one Republican (Kirk) rather than four running in deep-blue territory the presidential race is likely to ignore or bypass. It would be highly unusual for Democrats to sweep this many Senate races in key presidential battleground states while the top of their ticket is losing those states.

Problem 2: Five Votes Are Harder Than Four On top of the difficulty of capturing the four (net) Senate seats needed to retake the Senate is the difficulty of gaining the fifth Senate seat necessary to keep the Senate after January 20, when Biden would be replaced by a Republican Vice President who would cast tie-breaking votes. Put yourself in the shoes of Chuck Schumer, the likely new Democratic Leader after Harry Reid retires. You just regained a Senate majority. You have the chance to seize something of enormous value, yes: a lifetime Supreme Court appointment. To do so, you have to pass a filibuster rule change that strips the Senate minority of long-cherished rights and drastically reduces their power. But you also know that the result is to completely and irrevocably poison the well with Senate Republicans and the incoming Administration.

If you picked up five seats, this may seem like a worthwhile tradeoff and one that will allow you to rule the Senate with an iron fist and negotiate with the new Republican President and Speaker Ryan from a position of strength. But if you only gained four seats, your majority will only last three weeks, and you will have destroyed powers your own caucus will badly want to use to stop a united GOP with the White House and both Houses of Congress for the remaining two years. Heck, you might even get them so angry they decide to pass a Court-packing plan to add two new Justices, and you just disabled yourself from stopping it as well as denuding yourself of any possible arguments for doing so.

Problem 3: What About Red State Democrats? Finally, let’s recall that no matter the margin we’re discussing here, it would require a lockstep unified Democratic caucus. Schumer or whoever else replaces Reid may well have that on many issues, but a dramatic burning of bridges with socially conservative voters may not be one of them. There are five Democratic Senators who still represent states that even Mitt Romney carried in 2012: Heidi Heitkamp in North Dakota, Jon Tester in Montana, Joe Donnelly in Indiana, Joe Manchin in West Virginia, and Claire McCaskill in Missouri. All five are up for re-election in 2018, as are Democratic Senators in Florida, Virginia, Ohio, Pennsylvania and Wisconsin who rode the wave of Obama-driven turnout in 2012. And if any of those Senators did defect from the plan, they would face certain doom in a primary. No incoming Senate Majority Leader – who after all needs their votes to get the job on January 3 in the first place – would want to put so much of his caucus in that much peril right from the outset if he can avoid it.

Democrats may well win this fight, if they can recapture the White House. But unless they do so, the plan for a January Surprise is a spectacularly impractical one.

[Standard disclaimer: the above analysis assumes that the Republican Party continues to exist after mid-June. If Donald Trump were to capture enough delegates win the Presidential nomination, it would effectively dissolve the party, and any attempt to analyze the dynamics on Capitol Hill in terms of the existing two-party system would have to be recalibrated from scratch]